Peptic digestion of streptococcal M protein. I. Effect of digestion at suboptimal pH upon the biological and immunochemical properties of purified M protein extracts.
Purified streptococcal M protein vaccines often produce non-type-specific immunotoxic reactions in the skin or the blood of humans. In an attempt to free the type-specific M antigen (TSM) of such non-type-specific (NTSM) immunotoxic properties, purified M protein preparations were subjected to brief periods (5 to 10 min) of enzymatic digestion in dilute solutions of pepsin (20 mug/ml) at pH 5.0. Such peptic digestion abolished the ability of M protein to aggregate platelets in human platelet-rich plasma and to precipitate plasma fibrinogen. It greatly reduced (up to 16-fold) the capacity of M protein to react with the NTSM complement-fixing antibody that is normally present in human serum. In contrast, it had no effect upon the reactivity of the type-specific M antigen; the pepsin-treated M protein retained its ability to inhibit type-specific streptococcal opsonization by homologous M antibody, and, moreover, retained its ability to elicit type-specific opsonic antibody responses in rabbits.
D000917:Antibody Formation / Q000187:drug effects*; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D002850:Chromatography, Gel; D003168:Complement Fixation Tests; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen; D006863:Hydrogen-Ion Concentration; D005779:Immunodiffusion; D010434:Pepsin A; D010587:Phagocytosis / Q000187:drug effects*; D010973:Platelet Adhesiveness / Q000187:drug effects; D013297:Streptococcus pyogenes / Q000032:analysis / Q000276:immunology
D001426:Bacterial Proteins; D005340:Fibrinogen; D010434:Pepsin A