Immune unresponsiveness of spleen cells from lipopolysaccharide-treated mice to particulate thymus-dependent antigen. I. Evidence for differentiation signal defect.

The cellular basis of the immune unresponsiveness induced by lipopolysaccharide (LPS) was analyzed at the B and T cell level. The immunosuppressive effect of LPS is not related to altered B cell competence. Inhibition of antibody responses was observed only for thymus-dependent (TD) and not for thymus-independent antigens. In the presence of T cell-replacing factor (TRF), LPS-sensitized B lymphocytes respond to TD antigenic stimulation and differentiate into antibody-forming cells. Evidence is presented for a decreased helper activity of LPS-sensitized T lymphocytes and for a defective production of TRF in concanavalin A-stimulated spleen cells from LPS-treated mice. The implication of a cell compartment other than T is discussed.