Prolongation and enhancement of Nippostrongylus infection in the laboratory rat by a heterologous antiserum to rat peritoneal cells--a possible role for pharmacologically-active cells in immunity.

A rabbit anti-rat peritoneal cell (APCS) serum significantly suppresses (P<0.001) the immune response to Nippostrongylus brasiliensis infection in the rat and the infection can be prolonged by such an antiserum. The antiserum appeared to contain antibodies directed against the surface antigens of pharmacologically-active cells such as the mast cell. Prolongation of infection following treatment with APCS was accompanied by a reduction in the number of eosinophils, basophils and neutrophils in the peripheral circulation. The number of circulating peripheral lymphocytes was not significantly affected by the antiserum, nor did the antiserum affect the homograft response. This antiserum, however, suppressed the homologous PCA reaction and the response to an intradermal injection of histamine, and also provoked the complement-dependent release of histamine from mast cells in vitro up to a dilution of 1:512. It was estimated that the average rat mast cell contains 19.8 pg of histamine. These results provide evidence for the importance of eosinophils, basophils and mast cells, i.e. pharmacologically-active cells, in allowing the host to mount a homocytotropic antibody-allergen mediated reaction as part of the immune response.