concanavalin-a and Dermatomyositis

We studied an alpha-1-acid glycoprotein (AGP) and an alpha-1-antichymotrypsin (ACHT) microheterogeneity in sera of patients with polymyalgia rheumatica (PMR), giant cell arteritis (GCA/PMR), polymyositis/dermatomyositis (PM/DM) and healthy individuals by affinity electrophoresis with concanavalin A (Con-A) as the ligand. Our results are expressed as reactivity coefficients. The mean of AGP reactivity coefficients (AG-RC +/- SD) in PMR (0.92 +/- 0.17) and GCA/PMR (0.91 +/- 0.12) were significantly lower compared with the mean AG-RC in patients with PM/DM (1.48 +/- 0.52) as well as in healthy individuals (1.34 +/- 0.9). Moreover, an additional microheterogeneous form of AGP was noted in patients with PM/DM. In parallel, we also found that the mean of ACHT reactivity coefficients (AC-RC +/- SD) were lower in patients with PMR (2.94 +/- 1.24) and GCA/PMR (1.66 +/- 0.16) compared with healthy individuals (3.92 +/- 1.17). The mean of AC-RC in patients with PM/DM (6.74 +/- 4.35) was significantly higher than in patients with PMR and GCA/PMR as well as in healthy individuals. Our results show that the changes in reactivity of AGP and ACHT with Con-A are useful diagnostic markers for the differentiation of PMR and GCA/PMR from PM/DM.

Topics: Acute-Phase Proteins; Adolescent; Adult; Aged; Aged, 80 and over; alpha 1-Antichymotrypsin; C-Reactive Protein; Child; Child, Preschool; Concanavalin A; Dermatomyositis; Diagnosis, Differential; Electrophoresis; Female; Giant Cell Arteritis; Humans; Male; Middle Aged; Myositis; Orosomucoid; Polymyalgia Rheumatica

Polymyositis/dermatomyositis (PM/DM) is an autoimmune disorder of unknown aetiology. In order to study whether immunoregulatory abnormalities might be involved in this autoimmune state, we investigated the autologous mixed lymphocyte reaction (AMLR) and concanavalin A-induced suppressor cell function (Con A-induced suppression) in adult patients with primary PM/DM. We found the AMLR to be significantly depressed in patients; responsiveness could not be enhanced by increasing the numbers of non-T stimulator cells in culture, nor by varying the day on which cultures were harvested. Con A-induced suppression of T cell proliferative responses to mitogenic stimuli was normal. These findings implicate abnormal immunoregulation in the pathophysiology of PM/DM. Further, the dissociation of AMLR reactivity from Con A-inducible suppression suggests that events important for immunoregulatory competence may occur in the AMLR culture, despite the absence of an observed proliferative response.

Topics: Adult; Aged; Autoimmune Diseases; Concanavalin A; Dermatomyositis; Dose-Response Relationship, Immunologic; Humans; Leukocyte Count; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Middle Aged; Myositis; T-Lymphocytes, Regulatory