The elaboration of leukotactic mediators during the interaction between parental-type lymphocytes and F1 hybrid cells.

Mixed leukocyte cultures consisting of white blood cells from (Lewis times BN) F1 hybrids and Lewis parents produced monocyte chemotactic factor. Elaboration of this material preceded incorporation of 3H-thymidine. Local graft vs host (GVH) reactions were induced by subcapsular injection of parental thoracic duct cells into F1 hybrids. Homogenates from these kidneys, but not from kidneys injected with syngeneic thoracic duct cells, contained monocyte chemotactic factor. Little or no neutrophil chemotactic factor was present. Ultracentrifugal analysis of the monocyte chemotactic factor indicated a distribution similar to that found previously in culture fluids of lymphoid cells stimulated by soluble antigens. Differential counts of inflammatory cells extracted in suspension form from kidneys undergoing a GVH reaction indicated the majority of cells to be lymphocytic in type, but with a significant proportion of monocytes. Virtually no neutrophils were present. These findings indicate that a monocyte chemotactic factor is produced by cultures of parental leukocytes stimulated by semiallogeneic cells and that a similar factor appears in GVH reactions in the rat kidney. This chemotactic factor may be relevant to the character of the cellular exudates.