Endemic syphilis: transfer of resistance to Treponema pallidum strain Bosnia A in hamsters with a cell suspension enriched in thymus-derived cells.

Direct evidence for involvement of thymus-derived (T) cells in host defense against syphilitic infection is presented. Irradiated, bone marrow-reconstituted hamsters receiving cells from hamsters immune to infection with Treponema pallidum strain Bosnia A had significantly lower weights and fewer treponemes per lymph node than animals that had received normal lymphoid cells or only normal bone marrow cells. Cell suspensions enriched in T cells from immune hamsters were obtained by sequential filtration of pooled spleen and lymph node cells through glass- and nylon-wool columns. The fractionated suspensions of cells responded poorly to stimulation by phytohemagglutinin, Escherichia coli lipopolysaccharide, and dextran sulfate, but responded relatively strongly to the T-cell mitogen, convanavalin A. After fractionation the proportion of cells susceptible to antithymocyte serum and complement increased significantly. These immune cell suspensions depleted of bone marrow-derived cells closely resembled unfractionated suspensions in their ability to confer resistance to challenge with T. pallidium.