concanavalin-a and Trichinellosis

We examined apoptosis of eosinophils obtained from normal rats and rats infected with Trichinella spiralis (T. spiralis). A considerable percentage of normal rats underwent apoptosis within a few hours, however, the apoptosis rate of infected rats was significantly lower. This rate began decreasing only 12 h after infection, reached its lowest level on day 3, and was restored to normal by day 40. We also studied the effects on eosinophil apoptosis of culture supernatants from concanavalin A-stimulated spleen cells from infected rats and found that supernatants from days 3, 7, and 18 of infection inhibited apoptosis eosinophils from normal rats. We then examined the distribution and clearance of eosinophils in vivo. In normal rats, the largest numbers of eosinophils were found in the spleen, liver, and bone marrow. In the infected rats, however, by day 3, by which time the worms had begun to migrate, there was a striking increase in these cells in the intestines. In summary, normal eosinophils are unexpectedly sensitive to apoptosis, whereas infected eosinophils become resistant to this form of cell death.

Topics: Animals; Apoptosis; Cell Survival; Concanavalin A; Eosinophils; Immunologic Techniques; Interleukin-5; Rats; Rats, Wistar; Specific Pathogen-Free Organisms; Spleen; Trichinella spiralis; Trichinellosis

Trichinella spiralis-specific immunity can be transferred from immune mothers to suckling neonates via lactation, suggesting that milk from immune dams contains specific factors to T. spiralis. TNF and IL-6 are important cytokines in inflammatory processes, and IL-2 is essential in lymphocyte activation. Using cell line bioassays, we examined the capacity of rat milk mononuclear cells from immune and non-immune control dams to produce these cytokines following in vitro stimulation with mitogens or T. spiralis antigen. Milk cells were capable of producing IL-2, IL-6 and TNF upon Con A stimulation, and TNF and IL-6 upon LPS stimulation. The amount of these cytokines produced by mitogen-stimulated milk cells from T. spiralis-infected rats was similar to that produced by non-infected controls, although lower than that of corresponding blood mononuclear cells. Upon stimulation with T. spiralis antigen, milk cells from infected rats produced a significantly higher amount of TNF (158 +/- 39 U/10(6) cells) compared to non-infected controls (16 +/- 6 U/10(6) cells, P < 0.01), and also higher than that of the corresponding blood cells (60 +/- 10 U/10(6) cells, P < 0.01). Only small amounts of IL-6 and no IL-2 was secreted by milk cells from control or infected groups after stimulation with antigen. This study shows that rat milk cells are capable of synthesizing cytokines, and TNF produced by immune mothers may play a role in augmenting the neonate resistance to T. spiralis infection.

Topics: Animals; Animals, Suckling; Antigens, Helminth; Concanavalin A; Cytokines; Female; Immunity, Maternally-Acquired; In Vitro Techniques; Interleukin-2; Interleukin-6; Lipopolysaccharides; Milk; Pregnancy; Pregnancy Complications, Parasitic; Rats; Rats, Inbred F344; Trichinella spiralis; Trichinellosis; Tumor Necrosis Factor-alpha

Jejunal longitudinal muscle from Trichinella-infected Sprague-Dawley rats generates increased tension in vitro 6 days after infection. To investigate the extent to which this increase is dependent on T lymphocytes, smooth muscle contraction was examined in athymic rats (rnu/rnu) and in their euthymic (rnu/+) littermates 6 days after infection. In both thymus-bearing and athymic rats, the highest concentrations of Trichinella were found in the jejunum where mucosal myeloperoxidase activity was increased. Muscle from infected euthymic rats generated more tension to carbachol or 5-hydroxytryptamine than that of noninfected controls. In contrast, there was no difference between the responses of muscle from infected and control athymic animals. However, when athymic rats were reconstituted with splenic mononuclear cells, increased tension to carbachol or 5-hydroxytryptamine was observed after infection. T-lymphocyte activity was demonstrated by in vitro assays in euthymic or reconstituted rats but not in athymic rats. It is concluded that some changes in intestinal smooth muscle function following Trichinella spiralis infection in the rat are T lymphocyte dependent. These results support the concept of immunomodulation of intestinal smooth muscle function.

Topics: Analysis of Variance; Animals; Carbachol; Cell Division; Concanavalin A; Disease Models, Animal; Intestinal Diseases, Parasitic; Intestinal Mucosa; Jejunum; Male; Muscle Contraction; Muscle, Smooth; Peroxidase; Rats; Rats, Inbred Strains; Rats, Nude; Serotonin; Spleen; T-Lymphocytes; Trichinellosis

Although most intraepithelial lymphocytes (IEL) in mouse small intestine bear surface markers classically associated with T lymphocytes, the T-cell nature of these cells remains controversial. In the present study IEL from normal mice, or from mice infected with the gut nematode Trichinella spiralis, were therefore tested for their ability to produce T-cell-derived lymphokines in response to in vitro stimulation with concanavalin A (Con A) or with specific worm antigens. The data show that Con A-stimulated IEL produce minimal amounts of IL-2, and intermediate levels of IFN-gamma and IL-3 in comparison to the levels produced by spleen T cells. The FDC-P2 cell line, which proliferates in response to both IL-3 and GM-CSF, was identified as the most sensitive and reproducible indicator of lymphokine activity in supernatants from mitogen-stimulated IEL from normal mice. IEL isolated from mice infected with T. spiralis also produced high levels of FDC-P2 growth factors when challenged in vitro with Trichinella-derived antigens; however, normal IEL did not respond to this stimulus. The data thus provide evidence that antigen-sensitive T cells can arise in (or migrate to) the gut epithelium during gut infection.

Topics: Animals; Antigens; Concanavalin A; Epithelium; Intestine, Small; Lymphocyte Activation; Lymphokines; Male; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Mitogens; Neutralization Tests; Phenotype; T-Lymphocytes; Trichinellosis

Lectins which identify carbohydrates and glycoproteins have been used to characterize specific components of the surface of guinea pig peritoneal exudate eosinophils. Agglutination of eosinophils purified by discontinuous metrizamide gradients was scored microscopically. Wheat germ agglutinin (WGA) was most effective (0.05 micrograms/ml). However, higher concentrations of soybean lectin and concanavalin A (Con A) were also effective. No differences in lectin binding were noted between eosinophils harvested from uninfected animals, Trichinella spiralis-infected animals, or animals receiving weekly intraperitoneal injections of polymyxin B. Neuraminidase pretreatment to remove surface sialic acid reduced agglutination by WGA. Eosinophils did not adhere to WGA-coated Sepharose beads; however, they did adhere to Con A-coated beads. Pretreatment with neuraminidase did not affect the adherence of eosinophils to plastic surfaces, suggesting that sialic acid does not play an important role in adherence. Formation of lectin-inhibitor complexes within the incubation mixture complicated interpretation of studies of binding to plastic surfaces. These studies demonstrate that lectin binding sites are present on the surface of eosinophils. Lectin-type binding may be important in interactions between eosinophils and noningestible parasites.

Topics: Agglutination; Animals; Cell Adhesion; Concanavalin A; Eosinophils; Guinea Pigs; Lectins; Neuraminidase; Peritoneum; Trichinellosis

Topics: Animals; Cells, Cultured; Concanavalin A; Interleukin-2; Interleukin-3; Intestinal Mucosa; Lymphokines; Mast Cells; Mice; T-Lymphocytes; T-Lymphocytes, Regulatory; Trichinella; Trichinellosis

Topics: Animals; Antibody Formation; Concanavalin A; Immunity, Cellular; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Phytohemagglutinins; Time Factors; Trichinellosis