Antibody enhances lymphocyte proliferation in guinea pigs immunized to express cutaneous basophil hypersensitivity

Lymphocytes from HSA-sensitized guinea pigs expressing cutaneous basophil hypersensitivity (CBH) proliferate in the presence of specific antigen. We report that this proliferative response is enhanced by the addition of anti-HSA antibody, either in the form of whole immune serum or as purified antibody. The enhancement was characterized as a marked shift of the antigen dose-response curve such that significant [3H]thymidine incorporation was observed at antigen concentrations much lower than those eliciting a comparable response in the absence of immune serum. Enhancement was antigen specific and required an intact immunoglobulin molecule. Antibodies capable of enhancing antigen-specific lymphocyte proliferation could be isolated from serum by affinity chromatography as early as 7 days after sensitization and were also evident in sera obtained at later intervals. It is unlikely that such antibodies account for the progressive decline of CBH reactivity and they may actually influence its initial expression.