Influence of an M‐Locus Difference on the Cellular and Humoral Immunological Reactivity Against H‐2‐Determined Antigens of the Mouse

Studies were initiated to determine whether an immune response to the Mls antigen of C3H mice could modify responses of CBA lymphocytes (H-2-compatible) to a foreign H-2 complex. CBA lymphocytes, partially tolerant to the C5H-determined Mls antigen, generated less effector cell activity against C57Bl cells (H-2-incompatible) Chan lymph node cells from normal CBA donors when infused into irradiated C.3H × C57Bl hosts. Effector cell activity was measured as the capacity of the cells in the irradiated spleens to inhibit CBA × C57Bl bone marrow proliferation. In contrast, immunization of CBA mice with C3H × C57Bl cells yielded lower antibody titers against C577Bl cells than immunization with CBA × C57Bl cells. Furthermore, preinjection of CBA mice with C3H × CBA cells strongly reduced the capacity of the animals to produce antibodies against C57Bl cells. Thus, these data support the conclusion that an immune response to a foreign Mls antigen may either enhance or suppress an immune response to H-2-incompatible cells.