Comparison of the anti-laminin antibody response in patients with systemic lupus erythematosus (SLE) and parasitic diseases (filariasis).

In this study, we analyzed the presence of antibodies against the basement membrane antigen laminin (LMN) in patients with systemic lupus erythematosus (SLE), filariasis, and normal controls. By ELISA, 13.8% of SLE (12/87), 66.7% of parasitized patients (20/30), and two of the normal controls had these antibodies. IgG1 anti-LMN response was elevated in all groups, whereas IgG2 and IgG3 were also elevated in parasitized patients. The analysis of the IgG anti-laminin binding capacity in SLE and parasitized patients showed similar average antibody affinity. These antibodies did not react with fibronectin by a competition ELISA. By Western blot, the anti-laminin antibodies could be demonstrated in parasitized patient sera but not in SLE sera. Moreover, the ability of these antibodies to bind to heat-treated LMN (100 degrees C for 4 min) was different. The study of the binding capacity with native or denatured LMN by Western blot and dot-blot assays showed that the anti-LMN antibodies from parasitized patients were able to react with both native and denatured forms of LMN, whereas in SLE patients these antibodies were demonstrated only with native LMN. On the other hand, the reactivity detected in the normal control sera seems to be different from the anti-LMN antibodies from SLE and parasitized patients, and probably reflects the existence of natural antibodies in these sera. The presence of anti-LMN antibodies correlates significantly with the ability of inhibition of U937 cell adhesion to LMN-coated surfaces (P < 0.0025). The difference of anti-laminin reactivity suggests that antibodies produced following immunization with autoantigens or similar molecules present in parasites have different specificities from those spontaneously produced by individuals with autoimmune diseases.