THE SPECIFICITY PATTERNS OF HUMAN-IMMUNOGLOBULIN-G ANTIBODIES IN SERUM DIFFER FROM THOSE IN AUTOLOGOUS SECRETIONS

The specificity patterns of immunoglobulin G (IgG) antibodies to strep tococcal antigens in serum and autologous secretions were compared in order determine whether IgG found in human secretions is exclusively o f serum origin or can also be locally produced irrespective of the sys temic immune system. Surface antigens from a type 6 M-protein strain o f Streptococcus pyogenes were extracted by cell wall digestion and sub jected to sodium lauryl sulfate-polyacrylamide gel electrophoresis und er reducing conditions. After being blotted onto nitrocellulose, the a ntigens were incubated with purified IgG from various body fluids: sal iva, cervicovaginal secretions, seminal fluid, and colostrum. Binding was then revealed with labeled antibodies to human Fc gamma fragments. The antibody specificity patterns obtained by computer-assisted analy sis were compared with those of paired sera. Major variations were obs erved between serum and secretions, as well as between different secre tions from the same subject. These results are in favor of IgG-associa ted local immunity within different tissue compartments. This IgG resp onse to mucosal antigens can complement that of secretory IgA in the d efense against pathogens and should be taken into account during topic al vaccinations.