The immunodepressive effect of Friend virus. IV. Effects on spleen B lymphocytes.

Splenic immune responses having varying dependence on accessory cell co-operation have been studied after infection of mice with Friend virus. Infection has no effect on cell proliferation or antibody production in cultures stimulated with E. coli lipopolysaccharide. The response in vivo to type III pneumococcal polysaccharide is depressed only moderately. The response to sheep red blood cells is depressed severely both in vivo and in vitro. Depression in vitro is greatly reduced by co-stimulation with E. coli lipopolysaccharide. Depletion of potential suppressor lymphocyte populations by irradiation or adult thymectomy does not ameliorate depression of responses to sheep red blood cells or pneumococcal polysaccharide. Responses after adult thymectomy plus irradiation are not affected by the virus. Although it is known that macrophage and helper T-lymphocyte co-operation are not themselves impaired by infection, these results suggest that there is a direct relationship between severity of immune depression and dependence on co-operation. Implications for the action of the virus are discussed.