Non-H-2-linked difference in delayed-type hypersensitivity in mice

Significant difference in delayed-type hypersensitivity (DTH) to sheep erythrocytes (SRBC) and to Mycobacterium bovis BCG was observed between SJL/J (H-2^s) and A.SW (H-2^s) strains. SJL/J was a high responder in DTH to BCG but a low responder to SRBC, while A.SW mice showed a high response to SRBC but a low response to BCG. Cyclophosphamide treatment of these mice resulted in the enhanced DTH to the antigen in animals which were in low responsive state, while being unable to enhance the response of high responders. These results suggest that DTH to either SRBC or BCG is regulated by a gene(s) which is not linked to H-2, and that the low responsiveness is probably due to a suppressor mechanism.