Further studies on the enhancement of the antibody response in vitro by C. parvum

Abstract

We have shown previously that spleen cells from mice pre-treated with C. parvum give enhanced antibody response when cultured in the presence of thymus-dependent antigens. In order to establish if C. parvum has a similar effect when added in vitro, spleen cells from untreated mice were cultured with C. parvum in Marbrook chambers with sheep erythrocytes (SRBC) as antigen. At concentrations of 35-140 microgram/ml/20 x 10(6) spleen cells C. parvum enhanced, but at higher concentrations suppressed the in vitro response. Cultures containing lymphocytes from C. parvum treated mice and adherent cells from untreated animals, which do not show in vitro the enhancement in the absence of C. parvum, gave higher responses to SRBC when a critical dose of the vaccine was added. Supernatants from cultures of normal spleen cells with added C. parvum could enhance the in vitro response of normal spleen cells. In double Marbrook cultures, cells from mice pre-treated with C. parvum and cultured with this organism failed, however, to enhance the response of untreated cells in the outer vessel. Under these conditions the response was enhanced only when SRBC were also present in the inner vessel.