Persistence of Antibodies in Human Subjects Injected with Pneumococcal Polysaccharides

Abstract

Human subjects injected 3, 5 to 6, or 8 years previously with type-specific pneumococcal polysaccharides usually showed measurable and sometimes relatively high antibody levels when their sera were analyzed after the periods indicated. In instances in which an antibody had disappeared or remained only in small quantity, reinjection of the homologous polysaccharide usually caused antibody to reappear or to increase, although rarely to the original maximum. The lowered secondary response does not amount to a “paralysis” of antibody function and does not extend to primary formation of antibodies to polysaccharides not previously injected.