Circulating immune complexes, complement factors C3, C4, C1-inhibitor, alpha-1-antitrypsin and immunoglobulins in asthmatic patients.

Sera from 159 adult asthmatic outpatients (extrinsic, n = 82, intrinsic, n = 65 and acetylosalicylic acid (ASA)-sensitive, n = 12) and from 100 controls were tested for total levels of IgG, IgM, IgA, IgE, complement factors C3, C4, C1-inhibitor, alpha 1-antitrypsin and circulating immune complexes. The following results were observed: (1) a marked increase of IgE in extrinsic asthma; (2) a slight increase of IgM, and (3) an equal increase of complement C4 levels in all three asthma groups; (4) normal mean values of C3 levels with a significantly larger standard deviation of the mean in all three asthma groups; (5) an equally slight decrease of protease inhibitors, such as C1-inhibitor and alpha 1-antitrypsin, and (6) the presence of circulating immune complexes in 22% of extrinsic, in 8% of intrinsic and 13% of ASA-sensitive asthmatics. Circulating immune complexes can be found in all three asthma groups and may correlate with complement deviation.