Circulating antibodies to prothymosin α in systemic lupus erythematosus

Autoantibodies to prothymosin α, an immunoactive protein that exists in a large variety of mammalian tissues, were found to be present in patients with systemic lupus erythematosus (SLE) by a new, sensitive, and specific anti-prothymosin α ELISA. The antigen was prothymosin α, purified by high-pressure liquid chromatography from goat spleen extracts. Sera from 44 SLE patients and 276 healthy individuals were screened for the presence of anti-prothymosin α activity; 18% of SLE sera were found to be positive, compared with 1.8% of control sera. This anti-prothymosin α activity appears to be idiotypically distinct from either anti-thymosin α1 activity or anti-dsDNA activity, as demonstrated by inhibition experiments. Significant positive correlation exists between anti-prothymosin α and anti-dsDNA activities of SLE sera (r = +0.596, n = 36, P < 0.001), while no correlation was observed with the clinical activity (χ2 = 1.239, 0.1 < P < 0.5) or with complement levels C3 and C4.