Further studies on guinea pig and rabbit cytophilic antibodies directed against human serum albumin. II. In vitro binding properties and the role of cytophilic antibody in plague-formation as measured using the indirect technique of localized hemolysis in gel.

Abstract

The fixation of guinea pig and rabbit cytophilic antibodies to normal cells of homologous origin was investigated. For both systems, PE cells were found to fix antibody most efficiently. Spleen cells from other animal species were also shown to fix both guinea pig and rabbit cytophilic antibodies; human spleen cells showed the highest levels of fixation. Interference in the fixation of cytophilic antibodies to homologous spleen cells of guinea pig and rabbit origin was effected when absorptions were carried out in the presence of homologous and heterologous normal serum protein; with the guinea pig system, the presence of one ‘cytophilic’ antibody did not lead to levels of interference in antibody fixation of a second cytophilic antibody which were higher than those induced with normal serum proteins. Destruction of antibody receptor site activity by trypsin was not demonstrable for PE cells whereas the receptor site responsible for fixation of rabbit IgG but not IgM cytophilic antibody was shown to be highly susceptible to proteolytic enzyme treatment. Localized hemolysis in gel was produced using normal guinea pig and rabbit cells passively coated with homologous cytophilic antibody. Whereas the cytophilic antibody activity of guinea pig serum was previously shown to involve only the IgG class of immunoglobulins, the present report provides evidence for both IgM and IgG cytophilic antibody production in the rabbit.