Genetic Control of the In Vitro Responses of Rat Blood Lymphocytes

Abstract

Blood lymphocytes from the inbred rat strains AS and BN differ in the magnitude both of their in vitro proliferative response to different mitogens and of their in vivo antibody response to the mitogenic fraction of phytohemagglutinin (PHA). We have examined the segregation of in vitro responsiveness to PHA in (AS × BN)F1× BN backcross rats and have tried to correlate it with other characters that vary in backcross rats. In vitro responsiveness regulated by one or a few loci, is linked to the in vitro responsiveness to B lymphocyte mitogens and the in vivo antibody response to the mitogenic fraction of PHA, but is not linked to the major histocompatibility locus (Ag‐B) nor to the frequency of short‐lived, small Ig‐negative lymphocytes in blood. Lymphocytes from high‐responder rats have a shorter lag period before the onset of DNA synthesis in vitro than low‐responder rats, and possibly also a higher number of in vitro responding cells. To explain our findings, that the same gene og genes regulate in vitro responsiveness to different mitogens and in vivo antibody response to the mitogenic fraction of PHA, we suggest that the gene or genes act in an immunologically unspecific manner on regulation of lymphocyte proliferation in vitro as well as in vivo.

Genetic Control of Antibody Responses to PHA in Inbred Rats

“…During an investigation of the in vitro response to PHA of lymphoc)tes from different inbred strains of rats we observed great quantitativedifferences between individual strains. In particular, a low response was found with lymphocytes from BN rats (5). In further investigations we performed immuruwlectrophoretic analysis of PHA-P and purified several components by specific immunosorption and gel chromatography (3).…”

“…Perhaps the reason for this is associated with the fact that fraction D is a mixture of immunologically tross-reactive nwlecules with different biological properties (H). The purified D-fraction used in the present study represents the most anodal part of fraction D, which has strong mitogenic properties hut very little hemagglutinating activity (5).…”