Spleen hemolytic plaque-forming cell response and generation of cytotoxic cells in genetically obese (C57Bl/6J ob/ob) mice.

Cell-mediated immune responses were evaluated in genetically obese (C57Bl/6J ob/ob) mice and lean controls. The thymus and spleen weighed less and contained fewer mononuclear cells in obese animals compared with controls. The total number of direct and indirect plaque-forming cells in the spleen of obese mice immunized intraperitoneally with sheep red blood cells was reduced, however, when the results were expressed as plaques/10(6) mononuclear cells, the proportion of antibody-producing cells was higher in the obese. Ob/ob mice immunized in vivo with allogeneic EL-4 lymphoma cells showed markedly diminished capacity to generate cytotoxic cells, whereas such response after in vitro immunization was comparable in the two groups of animals. These observations suggest that altered cell-mediated immune response in obese animals is the result of a deleterious microenvironment.