IgA-alpha-1-antitrypsin complex in systemic lupus erythematosus: preliminary report.

To investigate the role of the complex IgA-alpha-1-antitrypsin (IgA-AT) in systemic lupus erythematosus (SLE) and in mixed connective tissue disease (MCTD), and its possible relations to either activity of the disease or a treatment, we examined a concentration of IgA-AT complex in 65 SLE and 9 MCTD sera. Complex IgA-AT was evaluated using a double antibody enzyme-linked immunoassay (ELISA). Twenty nine patients with SLE (44.6%) and three patients with MCTD (33.3%) had increased serum IgA-AT levels. The mean values of IgA-AT complex in patients with SLE and MCTD were higher than in healthy controls. Among the SLE group, patients with current neurological manifestation were characterized by an increase in IgA-AT serum concentration (2.45 +/- 2.07 U vs. 0.78 +/- 0.70 U, P < 0.001). No relation was found between this complex and ESR level, C-reactive protein (CRP) concentration, or hemoglobin level. Ten SLE patients were treated with CTX intravenously. In this group of patients, IgA-AT complex level was found to be increased compared with patients without such a treatment (1.82 +/- 1.30 U vs. 0.80 +/- 0.67 U, P < 0.05). The present study provides two new observations. Firstly, IgA-AT complex is increased in SLE and MCTD compared with healthy controls, and secondly, patients with CNS involvement displayed a striking increased IgA-AT level.