Genetic Control of B‐Cell Responses

The responsiveness of spleen cells from C3H/HeJ and C3H/Tif mice to lipopolysaccharide (LPS) was compared. Around 1,000‐fold higher concentration of LPS were required to minimally activate HeJ cells, as compared with Tif high‐responder cells, to both proliferation and polyclonal antibody secretion. However, HeJ cells did respond to higher LPS concentrations (100 and 1000 μg/ml). This selective pattern of responsiveness to LPS was also observed in the polyclonal responses of both strains to LPS in vivo. Furthermore, the unresponsiveness of HeJ spleen cells was found to depend on a pure B‐cell defect in the capacity to interact and/or generate triggering signals on interaction with LPS. Thus, adherent cells, thymus‐derived lymphocytes, serum factors, and other nonspecific conditions inherent in spleen cell suspensions of low‐responder mite were not responsible for suppressing a putative B‐cell response to LPS. The present findings are compatible with the possibility that the defect in C3H/HeJ B cells reflects the absence of a structure on the cell surface membrane that is functionally responsible for mediating LPS triggering.