concanavalin-a and Myasthenia-Gravis

Antibody-dependent cellular cytotoxicity (ADCC) was found to be significantly decreased in whole blood as well as in purified lymphocyte preparations from myasthenia gravis patients. Decreased ADCC was found not to correlate with the clinical classification nor with the therapy regimen, including immunosuppressive agents. PHA, Con A, and PPD responsiveness of peripheral blood lymphocytes was normal. Likewise no significant decrease was observed in the T-and B-cell distribution in the peripheral blood.

Topics: Adult; Aged; Antibodies; Autoantibodies; B-Lymphocytes; Concanavalin A; Cytotoxicity Tests, Immunologic; Female; Humans; Lectins; Lymphocyte Activation; Male; Middle Aged; Myasthenia Gravis; T-Lymphocytes; Tuberculin

The calcineurin inhibitors, tacrolimus and ciclosporin, are two useful immunosuppressive drugs for the treatment of myasthenia gravis (MG), for patients who have low responses to glucocorticoids. We have studied the suppressive potencies of tacrolimus and ciclosporin on concanavalin A-induced blastogenesis of peripheral-blood mononuclear cells (PBMCs) obtained from 38 MG patients and 26 healthy volunteers. Differences in the IC50 values of the two calcineurin inhibitors between the patients and the healthy subjects were evaluated. The median (range) IC50 values for tacrolimus and ciclosporin on the blastogenesis of PBMCs of MG patients were 0.06 (0.001-100) and 0.41 (0.09-83.0) ng mL(-1), respectively. In contrast, the median (range) IC50 values of tacrolimus and ciclosporin on healthy PBMCs were 0.16 (0.001-0.33) and 5.59 (1.4-31.3), respectively, and thus ciclosporin potencies against PBMCs of MG patients were significantly higher than those against PBMCs of healthy subjects (P < 0.0001). The differences in tacrolimus IC50 values between the patients and healthy subjects were not significant. There was a correlation between ciclosporin IC50 values against the blastogenesis of PBMCs of MG patients and the duration of the disease (r = 0.35, P = 0.049). A significant correlation between the IC50 values of ciclosporin and those of prednisolone against the blastogenesis of PBMCs of MG patients was also observed (r = 0.56, P = 0.003). Furthermore, the ciclosporin IC50 values significantly correlated with the periods of glucocorticoid administration for MG treatment (r = 0.42, P = 0.038). Such correlations were not observed with the tacrolimus IC50 values. These results suggested that glucocorticoid administration had an influence on PBMC response to the suppressive efficacy of ciclosporin in MG.

Topics: Adult; Calcineurin Inhibitors; Concanavalin A; Cyclosporine; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; Humans; Inhibitory Concentration 50; Leukocytes, Mononuclear; Lymphocyte Activation; Male; Middle Aged; Mitogens; Myasthenia Gravis; Tacrolimus

Myasthenia gravis (MG) and its animal model, experimental autoimmune MG (EAMG), are T cell-dependent antibody-mediated autoimmune diseases. A dual altered peptide ligand (APL) that is composed of the tandemly arranged two single amino acid analogues of two myasthenogenic peptides, p195-212 and p259-271, down-regulated in vitro and in vivo MG-associated autoreactive responses. The dual APL was shown to exert its beneficial effects by up-regulating ERK1,2 in CD4(+)CD25(+) regulatory cells. In this study, we investigated a novel 50-kDa ERK-like protein (ERK-50) that is up-regulated significantly in addition to ERK1,2 after treatment with the dual APL. We report here that ERK-50 was up-regulated in LN cells and in LN-derived T cells of mice that were immunized with the myasthenogenic peptides and treated with the dual APL. Moreover, ERK-50 was up-regulated in dual-APL- treated mice that were immunized with the Torpedo acetylcholine receptor. ERK-50 was demonstrated to be recognized by antibodies directed against the C and N termini of ERK1, against the C terminus of ERK2, and against general ERK. The 50-kDa ERK was shown to be stimulated by Con A, and inhibition of MEK1 down-regulated the 50-kDa ERK as was shown for ERK1,2. However, 4beta-phorbol 12-myristate 13-acetate (TPA) did not stimulate ERK-50. Finally, the activated ERK-50 was up-regulated in the dual-APL-induced CD4(+)CD25(+) regulatory cells. Thus, ERK-50 is suggested to be a novel ERK isoform, being up-regulated in response to treatment with the dual APL.

Topics: Animals; Cells, Cultured; Concanavalin A; Extracellular Signal-Regulated MAP Kinases; Female; Lymphocyte Count; Mice; Molecular Weight; Myasthenia Gravis; Peptides; Phosphorylation; Sensitivity and Specificity; T-Lymphocytes; Up-Regulation

Cytolytic T lymphocyte-associated antigen-4 (CTLA-4) plays a critical role in the down-regulation of antigen-activated immune responses. The aberrant CTLA-4 expression is characterized by low surface and intracellular levels of CTLA-4 protein, impaired up-regulation of CTLA-4 in T cells in response to ConA stimulation and high levels of soluble CTLA-4 (sCTLA-4) in serum. The serum levels of sCTLA-4 are positively correlated with the serum concentration of antibodies against the acetylcholine receptor. The (AT)(n) polymorphism in the 3'-untranslated region contributes to decreased mRNA stability and, hence, to reduced expression of CTLA-4.

Topics: Abatacept; Adult; Alleles; Antigens, CD; Antigens, Differentiation; AT Rich Sequence; CD28 Antigens; CD3 Complex; Cells, Cultured; Concanavalin A; CTLA-4 Antigen; DNA; Female; Gene Expression Regulation; HLA-DR Antigens; Humans; Immunoconjugates; Immunosuppressive Agents; Male; Middle Aged; Myasthenia Gravis; Polymorphism, Genetic; Receptors, Nicotinic; RNA, Messenger; T-Lymphocytes; Up-Regulation

Eleven patients with myasthenia gravis were followed for three years after thymectomy. Acetylcholine receptor-specific T-cell stimulation was found in 8/11 patients before operation as compared to 2/11 three years after thymectomy. Changes of T-cell antireceptor-reactivity were commonly paralleled by changes in disease severity. The numbers of cells secreting IL-2 upon stimulation with human acetylcholine receptor correlated with those secreting IFN-gamma. T-cell reactivity against a monoclonal acetylcholine receptor antibody did not decrease after thymectomy. Such reactivity could reflect a beneficial immune response counteracting anti-receptor reactivity. The frequency of autoantibody-secreting cells remained unchanged, while the serum concentration of acetylcholine receptor antibodies started to decrease one year after thymectomy. All examined thymus-cell suspensions contained autoreactive T- and B-lymphocytes. There was a preferential enrichment of autoreactive lymphocytes in the thymus in a few patients with recent onset of disease.

Topics: Adult; Aged; Antibodies; Antibodies, Monoclonal; Autoantibodies; Autoimmunity; B-Lymphocytes; Concanavalin A; Female; Humans; Interferon-gamma; Interleukin-2; Male; Middle Aged; Muscles; Myasthenia Gravis; Receptors, Cholinergic; T-Lymphocytes; Thymectomy

Interleukin-2 (IL-2) was demonstrated to induce interferon (IFN) production in the cultured lymphocytes from healthy donors and myasthenia gravis (MG) patients. Moreover, IL-2 enhanced lymphocytic IFN production in patients and healthy individuals in response to phytohemagglutinin and concanavalin A. However, in MG patients, IFN production in response to IL-2 alone or in combination with mitogens is several times lower than that in healthy donors. This lowered IFN production in MG patients is accompanied by much higher rates of lymphocytic proliferation and by considerably enhanced spontaneous lymphocytic production of C-reactive protein as compared with healthy individuals. This test may be of great value in establishing the diagnosis of an autoimmune disease, in defining its severity and in evaluating the efficiency of therapy.

Topics: Autoimmune Diseases; C-Reactive Protein; Cell Division; Cells, Cultured; Concanavalin A; Humans; Interferons; Interleukin-2; Lectins; Lymphocyte Activation; Lymphocytes; Mitogens; Myasthenia Gravis; Phytohemagglutinins; Recombinant Proteins

Nasal administration of nicotinic acetylcholine receptor (AChR) to Lewis rats prior to myasthenogenic immunization with AChR plus Freund's complete adjuvant (FCA) resulted in prevention or marked decrease of the severity of EAMG, suppression of AChR-specific B cell responses and of AChR-reactive T cell functions. To examine the involvement of immunoregulatory cytokines and the underlying mechanisms involved in tolerance induction, in situ hybridization with radio-labelled synthetic oligonucleotide probes was adopted to enumerate mononuclear cells (MNC) expressing mRNA for the proinflammatory cytokine IFN-gamma, the B cell stimulating IL-4 and the immune response-down-regulating TGF-beta. Popliteal and inguinal lymph nodes from EAMG rats contained elevated numbers of AChR-reactive IFN-gamma, IL-4 and TGF-beta mRNA-expressing cells compared with control rats receiving PBS nasally and injected with FCA only. Nasal tolerance to EAMG was accompanied by decreased numbers of AChR-reactive IFN-gamma and IL-4 mRNA-expressing cells, and strong up-regulation of TGF-beta mRNA-positive cells in lymphoid organs compared with non-tolerized EAMG control rats. The relative affinity of anti-AChR antibodies was lower, but muscle AChR amounts were higher in nasally tolerized rats compared with non-tolerized EAMG control rats. The results suggest that IFN-gamma and IL-4 are central effector molecules in the development of EAMG, and that TGF-beta plays an important role in tolerance induction to EAMG.

Topics: Administration, Intranasal; Animals; Concanavalin A; DNA Probes; Electrophoresis, Polyacrylamide Gel; Female; Immune Tolerance; Immunoglobulin G; In Situ Hybridization; Interferon-gamma; Interleukin-4; Leukocytes, Mononuclear; Lymph Nodes; Muscles; Myasthenia Gravis; Myelin Basic Protein; Oligonucleotides; Rats; Rats, Inbred Lew; Receptors, Nicotinic; RNA, Messenger; Transforming Growth Factor beta; Up-Regulation; Vaccination

Experimental autoimmune myasthenia gravis (EAMG) is a well established animal model, which can be induced in various animal species and strains with acetylcholine receptor (AChR) and represents an experimental counterpart of human myasthenia gravis (MG). Current immunotherapies of both EAMG and MG are non-specific and limited by their toxicity. Tolerance to EAMG has been achieved by oral administration of milligram quantities of Torpedo AChR. In the present report we demonstrate that nasal administration of microgram doses of Torpedo AChR to female Lewis rats prior to immunization with Torpedo AChR and complete Freund's adjuvant resulted in the prevention of subsequently induced EAMG, the suppression of serum anti-AChR antibody levels, the decrease of delayed-type hypersensitivity responses to AChR, as well as the suppression of AChR-specific immunoglobulin G-secreting cells, AChR-reactive interferon-gamma-secreting cells and T cell proliferation in peripheral lymphoid organs, particularly in popliteal and inguinal lymph nodes regional to immunization. We conclude that clinical signs of EAMG can be efficiently prevented by nasal administration of AChR in parallel with the downregulation of both B and T cell responses specific to AChR.

Topics: Administration, Intranasal; Animals; Concanavalin A; Electric Organ; Enzyme-Linked Immunosorbent Assay; Female; Hypersensitivity, Delayed; Immunoglobulin G; Interferon-gamma; Lymphocyte Activation; Myasthenia Gravis; Myelin Basic Protein; Rats; Rats, Inbred Lew; Receptors, Cholinergic; Time Factors; Torpedo

Lymph nodes, spleen and thymus obtained from Lewis rats were examined over the course of experimental autoimmune myasthenia gravis (EAMG) for the distribution and the number of antigen-reactive CD4+ T helper cells which, upon recognition of Torpedo acetylcholine receptor (AChR) or the alpha, beta, gamma or delta subunits of Torpedo AChR, responded by secretion of interferon-gamma (IFN-gamma). T cells with these specificities were detected in these three immune organs. Numbers were highest in lymph nodes. In spleen and thymus, numbers of antigen-reactive T cells did not differ. T cells reacting against the intact AChR were more frequent than T cells recognizing any of the subunits. The immunogenicity between the four subunits did not differ, with the exception that the alpha subunit induced a slightly higher T-cell response. No restriction of the T-cell repertoire to the four subunits was detected during early compared to late phases of EAMG. The AChR and subunit-reactive T cells could--via secretion of effector molecules including IFN-gamma--play an important role in the initiation and perpetuation of EAMG, and consequently also of human myasthenia gravis. T cells with the same specificities were also detected in control animals injected with adjuvant only, but at much lower numbers which were within the range of T cells recognizing the control antigen myelin basic protein. They could represent naturally occurring autoimmune T cells.

Topics: Animals; Autoimmune Diseases; Concanavalin A; Disease Models, Animal; Electrophoresis, Polyacrylamide Gel; Epitopes; Female; Interferon-gamma; Lymph Nodes; Lymphocyte Activation; Myasthenia Gravis; Peptide Fragments; Rats; Rats, Inbred Lew; Receptors, Cholinergic; Spleen; T-Lymphocytes; Thymus Gland

The activities of Con A-induced Suppressor Cells (Con-ASC) were determined in 50 patients with myasthenia gravis (MG) and 24 healthy controls. The ConA-SC activity of the patients with MG was significantly decreased as compared with that of the controls (10.06%) versus 25.28%, (P less than 0.01). Furthermore, the patients with generalized myasthenia gravis (GMG) had a lower ConA-SC activity than those with extraocular muscle myasthenia gravis (EMMG) (9.37% versus 12.13%, P less than 0.05), but their serum anti-acetylcholine receptor antibody titer was higher than that of patients with EMMG (20.55 x 10(-9) M versus 2.4 x 10(-9) M, P less than 0.01). No correlation found between the ConA-SC activity and the sex or duration of disease of the MG patients. And no effects of prednisone and thymectomy were found on the ConA-SC activity of MG patients. The results of the study suggested that the decreased function of suppressor T lymphocytes might play an important role in the pathogenesis of MG.

Topics: Adolescent; Adult; Aged; Child; Concanavalin A; Female; Humans; Male; Middle Aged; Myasthenia Gravis; T-Lymphocytes, Regulatory

Immunization with antigen-specific T cells has been used successfully in the treatment of several T cell-mediated experimental autoimmune diseases, including experimental allergic encephalomyelitis, thyroiditis, and adjuvant arthritis. The aim of this study was to determine whether T-cell vaccination could be used to down-regulate specifically the antibody response to AChR in experimental autoimmune myasthenia gravis (EAMG), an antibody-mediated disorder. We produced T cells specific for the acetylcholine receptor (AChR) by immunizing Lewis rats with torpedo AChR, harvesting the regional lymph node cells, and restimulating them in vitro with AChR. This cell population was expanded with IL2. The cells were then activated with concanavalin A (Con-A) and exposed to high hydrostatic pressure to augment their immunogenicity. We found that rats vaccinated with these cells did not manifest decreased antibody titers to AChR, when challenged. In fact, the antibody response to AChR was consistently potentiated by the vaccine treatment. This result could not be attributed to antigen carryover by the vaccinating cells or to induction of anti-idiotypic antibodies. Despite these results showing overall enhancement of the AChR antibody response, we found evidence of AChR-specific suppressor cells in the spleens of the vaccinated animals. Our observations indicate that T-cell vaccination can elicit both a positive immune response and a suppressive response in the same animal. If the T-cell vaccination strategy is to be useful for the treatment of MG, methods for amplifying the suppressive effect will need to be developed.

Topics: Animals; Antibodies, Anti-Idiotypic; Antibody Formation; Autoantibodies; Concanavalin A; Female; Hydrostatic Pressure; Immune Tolerance; Immunoglobulin Idiotypes; Interleukin-2; Lymph Nodes; Lymphocyte Activation; Myasthenia Gravis; Rats; Rats, Inbred Lew; Receptors, Nicotinic; T-Lymphocytes; T-Lymphocytes, Regulatory; Vaccination

In order to obtain a better understanding of the immunological abnormalities present in myasthenia gravis (MG), which is often accompanied by thymoma or thymic hyperplasia, we investigated lymphocyte subsets and their functions using samples of thymoma or thymic hyperplasia tissues from 11 patients (6 cases with MG), and peripheral blood from 6 patients (4 cases with MG). In most thymic tissues from patients with MG, a maturating tendency of lymphocytes was generally observed. Especially in the medulla of thymic hyperplasia, an entirely peripheral blood type of T-lymphocytes, which were Leu-6- and either Leu-2a+ or 3a + 3b+, were encountered abundantly. Therefore, the presence of abnormal maturation of lymphocytes in the thymus or destruction of the barrier between the thymus and the peripheral blood in MG cases was indicated. In cases without MG, no such tendency was noted. As to the peripheral blood in patients with MG, concanavalin A-induced suppressor cells were significantly decreased (p less than 0.01). All of these changes were considered to be intimately related to the appearance of MG.

Topics: Adult; Aged; Antigens, Differentiation, T-Lymphocyte; Child; Concanavalin A; Female; Humans; Immunohistochemistry; Male; Middle Aged; Myasthenia Gravis; T-Lymphocytes; Thymoma; Thymus Gland; Thymus Neoplasms

We have examined the localization of phospholipid/calcium-dependent protein kinase (protein kinase C) in thymoma cells, which were resected from a patient with myasthenia gravis. Upon stimulation with 4 micrograms/ml of concanavalin A (Con A) for 30 min, protein kinase C activity in the cytosolic fraction was increased from 7.44 pmol/min per 10(7) cells to 11.42 pmol/min per 10(7) cells. On the other hand, membrane-associated protein kinase C activity was decreased from 1.69 to 0.71 pmol/min per 10(7) cells. On the contrary, 10(-7) mol/l tetradecanoyl phorbol acetate (TPA) decreased cytosolic protein kinase C activity from 9.31 to 8.04 pmol/min per 10(7) cells, while membrane-associated protein kinase C activity was increased from 1.69 to 2.94 pmol/min per 10(7) cells. Several endogenous phosphorylated proteins (mol wt 20,000, 23,000) were observed as inferred by SDS-polyacrylamide gel electrophoresis. These findings indicated that Con A and TPA produce differential translocation of protein kinase C.

Topics: Concanavalin A; Cytosol; Electrophoresis, Polyacrylamide Gel; Female; Humans; Middle Aged; Myasthenia Gravis; Phorbol Esters; Phosphorylation; Protein Kinase C; Subcellular Fractions; Thymoma; Thymus Neoplasms

T-Lymphocyte number and functions are often reduced, while B-lymphocyte function is often increased in patients with autoimmune disorders. To study the mechanisms responsible for these T-cell malfunctions in autoimmunity we adapted the murine experimental autoimmune myasthenia gravis (EAMG) model. Splenocytes from C57BL/6 mice immunized with acetylcholine receptors (AChR) in complete Freund's adjuvant (CFA) produced approximately half the amount of concanavalin A (Con A)-induced interleukin 2 (IL-2) as did splenocytes of CFA-inoculated controls. Further, AChR plus CFA-immunized splenocytes showed a marked reduction in T-cell proliferative responses induced by Con A or phytohemagglutinin when compared with CFA-inoculated controls. By contrast, lipopolysaccharide-induced B-cell function is preserved. Deficient Con A splenic T-cell response is seen early after secondary inoculation with CFA or AChR in CFA. T-Cell recovery occurs in CFA-inoculated mice but not in AChR plus CFA-inoculated mice. Defective Con A splenic T-cell response seen early after secondary immunization with CFA or AChR in CFA is due to the presence of a defective splenic adherent cell population. Moreover, defective Con A splenic T-cell response seen after established autoimmunity to AChR in EAMG is also due to the presence of a defective splenic adherent cell population.

Topics: Animals; Autoimmune Diseases; Cell Adhesion; Concanavalin A; Female; Freund's Adjuvant; Immunity, Cellular; Immunization, Secondary; Immunologic Deficiency Syndromes; Interleukin-2; Kinetics; Lymphocyte Activation; Mice; Myasthenia Gravis; Receptors, Cholinergic; Spleen; T-Lymphocytes; T-Lymphocytes, Regulatory

The interactions of the nicotinic acetylcholine receptor (AChR), extracted from denervated rat hindlimb muscle, with alpha-bungarotoxin, Concanavalin-A (Con-A) and immunoglobulins isolated from the sera of specific patients with Myasthenia Gravis (MG) have been studied. The association and dissociation of toxin to unfractionated receptors [hydroxylapatite (HTP)-AChR] were best described in terms of two classes of kinetically distinct toxin binding sites present in approximately equal amounts. Incubation of these receptors with soluble Con-A decreased the total toxin-binding capacity by a maximum of 42%. Kinetic studies indicate that the Con-A-induced inhibition of toxin binding is restricted to those toxin binding sites having the fast rate of association with alpha-bungarotoxin. Incubation of HTP receptors with toxin blocking antibodies (MG-B) from MG patient sera decreased the toxin binding capacity by a maximum of 30%. By contrast, receptors fractionated by elution from Lens-Culinaris agarose affinity columns exhibited only fast rates of association and dissociation with alpha-bungarotoxin and represented 40% of the total HTP-AChR population. Con-A totally prevented toxin binding whereas MG-B antibodies had no blocking effect on this subpopulation of receptors. Another MG antibody type which interferes with lectin binding to AChR (MG-C antibody) gave a 50% maximum inhibition of both HTP- and Lens culinaris agarose-AChR. This suggests that both types of toxin binding sites (fast and slow) may be further divided into two separable subclasses based on their carbohydrate moieties. These results show that multiple forms of AChR occur in denervated muscle. At least two different forms of receptors are present which show distinctive differences in ligand-binding properties and some antigenic determinants.

Topics: Animals; Binding Sites; Bungarotoxins; Concanavalin A; Humans; Immunoglobulins; In Vitro Techniques; Kinetics; Myasthenia Gravis; Rats; Receptors, Cholinergic; Time Factors

Using in vitro lymphocyte proliferation induced by the phytomitogen concanavalin A (Con A), we investigated immune function and regulation in patients with myasthenia gravis (MG) and multiple sclerosis (MS). Unfractionated peripheral blood mononuclear cells of normal individuals responded to a wide range of ConA concentrations; the T cell fraction responded to a lesser degree and only to high concentrations. These findings suggest the presence of two receptors for ConA, one of high affinity present on a non-T cell accessory cell and the other of low affinity present on T cells. Contrasting defects in the level of response of unfractionated lymphocytes and T cells were found in patients with MG and MS. The peak response of T cells in the MG patients was 22.6 +/- 9.6 X 10(3) cpm (mean +/- SEM) compared with 54.6 +/- 6.5 X 10(3) for controls (p less than 0.05), while the response of unfractionated lymphocytes did not differ from that in controls. For MS patients, the unfractionated lymphocyte response was diminished: 56.3 +/-2.8 X 10(3) cpm versus 70.5 +/- 4.5 X 10(3) for controls (p less than 0.05), while the T cell response was normal. These results indicate a defect in the direct T cell response in MG; in contract, in MS the response requiring T cell-accessory cell interaction is abnormal.

Topics: Adult; Aged; Concanavalin A; Dose-Response Relationship, Drug; Humans; Lymphocyte Activation; Middle Aged; Monocytes; Multiple Sclerosis; Myasthenia Gravis; Rosette Formation; T-Lymphocytes

Functional T cell subsets have been evaluated in the peripheral blood of patients with myasthenia gravis using monoclonal anti-T cell antibodies and a suppressor cell assay based on the suppression of the mixed-lymphocyte reaction by concanavalin A-activated lymphocytes. A significant decline of suppressor cells was found in a large proportion of patients, both by direct count using the anti-suppressor-cytotoxic T cell antibody (OKT8) and by the suppressor assay. Patients also showed an increase in immature T cells defined by their simultaneous reaction with the anti-helper cell (OKT4) and anti-suppressor cell (OKT8) antibody. Thymectomy tended to enhance the deficit in suppressor cells, and to induce the disappearance of double-labelled cells.

Topics: Adolescent; Adult; Aged; Antibodies, Monoclonal; Antibody Specificity; Antilymphocyte Serum; Cell Division; Concanavalin A; Female; Humans; Leukocyte Count; Lymphocyte Activation; Male; Middle Aged; Myasthenia Gravis; Phytohemagglutinins; T-Lymphocytes; T-Lymphocytes, Regulatory; Thymectomy

Topics: Concanavalin A; Cytotoxicity, Immunologic; Humans; Immunoglobulin G; Immunoglobulin M; Lymphocyte Activation; Lymphocytes; Myasthenia Gravis; Rosette Formation; T-Lymphocytes, Regulatory

Topics: Adult; Aged; Concanavalin A; HLA Antigens; Humans; Lymphocyte Activation; Middle Aged; Myasthenia Gravis; Phytohemagglutinins; Pokeweed Mitogens; T-Lymphocytes, Regulatory

Topics: Antibodies; Binding, Competitive; Carbohydrates; Concanavalin A; Humans; Immunoassay; Myasthenia Gravis; Receptors, Cholinergic

1-Chloro-2,4-dinitrobenzene (DNCB) contact sensitivity and other T lymphocyte functions were studied in thymectomized and non-thymectomized patients with myasthenia gravis. The ability to develop contact sensitivity was reduced in patients with myasthenia gravis and was further reduced after thymectomy. Memory lymphocyte function, as measured by skin tests with common microbial antigens, was intact. A positive phytohemagglutinin (PHA) skin test was found mainly in those patients who also developed contact sensitivity to DNCB. The number of rosette-forming T cells in the peripheral blood as well as mitogen stimulation with PHA was found to be normal in thymectomized as well as non-thymectomized patients. In the thymectomized group, mitogen stimulation with concanavalin A and staphylococcal protein A was also within the normal range, while increased stimulation was obtained with pokeweed mitogen (PWM) and purified protein derivative (PPD). No alteration in mixed lymphocyte culture reactivity or immunoglobulin levels was obtained compared with healthy blood donors. On the basis of these results, it is concluded that non-thymectomized as well as thymectomized patients with myasthenia gravis may have a defective subpopulation of T cells possibly residing in the TH1-positive population. Furthermore, the increased lymphocyte stimulation obtained with PPD and PWM may indicate a reduction of suppressor cell activity after thymectomy.

Topics: Adolescent; Adult; Aging; Cholinesterase Inhibitors; Concanavalin A; Dermatitis, Contact; Dinitrochlorobenzene; Female; Humans; Male; Middle Aged; Myasthenia Gravis; Phytohemagglutinins; Pokeweed Mitogens; Skin Tests; Staphylococcal Protein A; T-Lymphocytes; Thymectomy; Tuberculin

Alterations of membrane surface and membrane microviscosity were studied in peripheral blood lymphocytes from myasthenic patients and compared with those from healthy subjects and SLE patients. The membrane ultramicrostructure of myasthenic lymphocytes was changed less than those of healthy and SLE lymphocytes. It showed slightly clustered MAP with larger diameters and less density than the healthy lymphocytes and with less prominent wavy surfaces than SLE lymphocytes. The microviscosity of the myashtenic lymphocytes was significantly lower that of the healthy controls and correlated well with clinical severity and the titers of anti-AchR anti-body and T cell membrane binding antibody. Con A, AHLA, and myasthenic sera reduced the microviscosities of the healthy lymphocytes. These results showed that the morphological changes of the lymphocyte surface were reflected in the alteration of microviscosity of lymphocytes through the interaction between surface receptors of T lymphocytes and anti-membrane antibody, especially anti-AchR antibody and T cell membrane binding antibody in patients with myasthenia gravis.

Topics: Antilymphocyte Serum; Cell Membrane; Concanavalin A; Freeze Fracturing; Humans; Myasthenia Gravis; T-Lymphocytes; Viscosity

Topics: Adult; Aged; Antilymphocyte Serum; Cold Temperature; Concanavalin A; Female; HLA Antigens; Humans; Lymphocyte Activation; Male; Middle Aged; Myasthenia Gravis; Pedigree; Phytohemagglutinins; Receptors, Fc; T-Lymphocytes, Regulatory

Peanut agglutinin (PNA) has previously been shown to be a 'marker' for early T subpopulations in mice. We have investigated whether it could also be used in the study of human mononuclear cells. 50--60% of human thymocytes have binding sites for PNA. When separated on a discontinuous Ficoll gradient, the PNA-positive thymocytes are found preferentially in the layers corresponding to the immunoincompetent cells. In the peripheral blood only 5% of the mononuclear cells are PNA-positive and we have shown that these cells are monocytes. In tonsils 13% of PNA+ cells are found and they are mostly lymphocytes. Thus, PNA is a marker for some T cell subsets present in the thymus and tonsils.

Topics: Adult; Aged; Arachis; Binding Sites; Cell Separation; Child; Child, Preschool; Concanavalin A; Humans; Immunoenzyme Techniques; Immunologic Techniques; Infant; Lectins; Lymphocyte Activation; Middle Aged; Monocytes; Myasthenia Gravis; Palatine Tonsil; Plant Lectins; Rosette Formation; Spleen; T-Lymphocytes; Thymus Gland

Topics: Aged; Concanavalin A; Humans; Middle Aged; Multiple Sclerosis; Myasthenia Gravis; T-Lymphocytes

Thymectomy in adult animals impairs immune functions such as lymphocyte response to phytohemagglutinin (PHA) and to allogeneic cells. The responses of lymphocytes from 18 myasthenia gravis patients, 12 of whom had undergone thymectomy, were studied; the interval between thymectomy and investigation ranged from 1 month to 26 years (mean, 9.5 years). Peripheral blood lymphocytes were cultured in autochthonous plasma or homologous AB serum. In vitro responses to stimulation with PHA, concanavalin A and allogeneic monomuclear cells were within the 95% range of normal responses in all patients. Because our findings contrast with the definite immune defects resulting from thymectomy found in adult animals, longer follow-up is needed.

Topics: Adolescent; Adult; Aged; Concanavalin A; Female; Humans; Immunity, Cellular; Lymphocyte Activation; Lymphocytes; Male; Middle Aged; Myasthenia Gravis; Thymectomy

Since the blood and thymus of patients with myasthenia gravis may contain inhibitors of neuromuscular transmission that affect acetylcholine receptors of striated muscle, we used denervated rat muscle to test for inhibitors in 43 serums and 18 thymus glands from such patients. Seven per cent of serums inhibited the binding of 125l alpha-bungarotoxin to triton-solubilized receptors; 65 per cent interfered with binding of toxin-labeled receptors to concanavalin-A coupled to Sepharose gel, and 85 per cent formed IgG-receptor complexes detectable by immunoprecipitation. Serum inhibitory activity varied widely among patients with similar clinical manifestations and was not correlated with duration of myasthenia gravis or thymectomy. Among thymus extracts, 44 per cent were inhibitory in the concanavalin-A binding assay, whereas 72 per cent contained anti-receptor IgG. Thus, serums from patients with myasthenia gravis contain more than one anti-receptor factor.

Topics: Acetylcholine; Animals; Autoantibodies; Autoimmune Diseases; Binding Sites, Antibody; Bungarotoxins; Chromatography; Concanavalin A; Female; Humans; Immunoglobulin G; Male; Methods; Muscles; Myasthenia Gravis; Rats; Receptors, Cholinergic; Thymus Extracts; Thymus Gland

Topics: Acetylcholine; Adult; Brain; Brain Chemistry; Breast Neoplasms; Bronchial Neoplasms; Carcinoma; Cell Migration Inhibition; Concanavalin A; Epinephrine; Epitopes; Female; Histamine; Humans; Laryngeal Neoplasms; Lymphocytes; Macrophages; Male; Middle Aged; Myasthenia Gravis; Neoplasm Proteins; Neoplasms; Nerve Tissue Proteins; Norepinephrine; Sarcoidosis; Serotonin; Stomach Neoplasms; Succinylcholine; Tryptamines