Elevated plasma levels of alpha 2-plasmin inhibitor-plasmin complex in patients with rheumatic diseases. Possible role of fibrinolytic mechanism in vasculitis.

Plasma levels of alpha 2-plasmin inhibitor (alpha 2PI) and alpha 2-plasmin inhibitor-plasmin complex (alpha 2 PIPC) were measured by sandwich enzyme-linked immunosorbent assay, using a recently developed monoclonal anti-alpha 2PI antibody, in patients with collagen diseases. Twenty patients had systemic lupus erythematosus (SLE), 4 of whom also had vasculitis, 11 patients had rheumatoid arthritis (RA), 4 of whom also had vasculitis, and 5 patients had other types of vasculitis. There was no significant difference in alpha 2PI levels between the 3 patient groups and the control groups. However, plasma levels of alpha 2PIPC in all 3 patient groups were significantly higher than those in the control group. Moreover, plasma concentrations of alpha 2PIPC in SLE patients with vasculitis were statistically significantly higher than those in SLE patients without vasculitis. These concentrations were also higher in RA patients with vasculitis than in RA patients without vasculitis, although the difference was not statistically significant. Our findings indicate that measurement of plasma alpha 2PIPC levels is useful for detecting and evaluating the severity and activity of vasculitis in patients with collagen diseases.