Alteration in graft vs host reactivity and in hematopoietic stem cells of spleen cell inocula from donor mice pretreated with pertussis antigen.

The graft versus host reactivity (GVHR) and hematopoietic stem cells of spleen cell inocula were assayed 3 days after pretreatment of donor mice with heated or unheated pertussis vaccine. Unheated vaccine reduced GVHR to 17 percent of control reactivity, measured by the Simonsen spleen weight assay, and increased 2. 2-fold the proportion of hematopoietic stem cells, assayed as colony forming units (CFU). Heated vaccine, which did not produce the lymphocytosis induced in donors by unheated vaccine, reduced GVHR to 38 percent of control reactivity, and increased the proportion of CFU 3.8-fold. Alternative mechanisms for these effects are discussed.