High levels of antibodies to streptococcal cell membrane antigens specifically bound to monoclonal antibodies in acute poststreptococcal glomerulonephritis.

We produced 15 immunoglobulin G class monoclonal antibodies against antigens of the streptococcal cell membrane (SCM) of Streptococcus pyogenes (T type 12, Tanaka strain) and determined the levels in human sera of antibodies against Triton-X-extracted antigens specifically bound to each of these 15 monoclonal antibodies by enzyme-linked immunosorbent assay. Sample sera were obtained from 10 normal controls (group 1), 10 patients with streptococcal pharyngitis without sequelae (group 2), and 8 patients with acute poststreptococcal glomerulonephritis (APSGN) (group 3). Anti-streptolysin O (ASO) titers of the sera increased in the order of groups 1, 2, and 3. There was no relationship between ASO titer and the level of anti-SCM antibodies, and there was no significant difference in the level of anti-SCM antibodies determined with each of the 15 monoclonal antibodies between group 1 and group 2 sera. Group 3 sera had higher levels of antibodies to SCM antigens specifically bound to each of 14 of these 15 monoclonal antibodies than group 1 or group 2 sera did. Of these 14 monoclonal antibodies, 9 reacted with the four SCM antigens separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to a nitrocellulose sheet. These results suggest that high levels of antibodies to SCM antigens are related to the development of APSGN and that the systemic immune response to SCM antigens is involved in the pathogenesis of APSGN.