Estimation of specific streptococcal antibodies from immune complexes in sera of patients with post-streptococcal acute glomerulonephritis - abstract

ABSTRACT

The enzyme-linked immunoabsorbent assay (ELISA) was used to determine the specific streptococcal antibodies in the sera of patients with post-streptococcal acute glomerulonephritis. Attempts to use this same technique to determine the immunoglobulin content of immune complexes (IC) after immunochemical dissociation proved futile. It became necessary to perform an inhibition assay before performing the ELISA. This modification involved the determination of the antigen concentration necessary to produce 50 per cent inhibition of the dissassociated antibody. The antigen inhibitors, M-types 41 and 55 cell membranes, were found to inhibit optimally at 12.5 ug/ml and were used to absorb dissassociated immune complexes diluted 1/00. The absorbed solution was then used in the ELISA test system. While specific streptococcal antibodies to M-55 were lower than those to M-41 (p<0.001) in PSAGN patients and those in controls (p<0.001), in the IC controls, specific antibodies to both inhibitors were of the same order. In PSAGN, however, the antibody levels were increased when compared with controls. Interestingly enough, specific streptococcal antibodies were demonstrated in IC of resolved GN cases, chronic GN and in those with intermittent proteinuria (AU)