Physiologic and pharmacologic alterations of rat leukocyte chemotaxis (Cx) in vivo

The method of adoptively transferring 51Cr-labeled rat leukocytes iv to isologous recipients was used to quantitate the extravascular accumulation of specific cell types at the site of inflammation induced by local injection of various phlogistic agents. Experiments were designed to determine whether cellular accumulation could be modified at the level of the chemotactic factor, by serum components, or by alteration of the responding cell itself. The results indicated a selective attraction of mononuclear cells to the local injection site of BCG and of neutrophils to the injection site of aggregated but not monometric gamma-globulin. Thus, leukocytic accumulation was found to be dependent upon the local generation of specific reactants that were particular to the agent employed. Leukocytic accumulation could also be modified by serum factors. Cellular accumulation was inhibited when leukocytes were exposed to serum that contained phagocytosable particles or after phagocytosis in vitro prior to adoptive transfer. Chemotaxis of lymphocytes could be induced by their preincubation with sera from adjuvant arthritic animals. These observations were confirmed by in vitro studies and by the finding that 6 days after adjuvant injection , lymphocytes but not mononuclear cells accumulated at the noninjected extremity. In the final series of experiments, it was shown that BCG immunization was capable of inducing a unique population of peritoneal mononuclear cells that after adoptive transfer had an enhanced capacity to remain in the circulation, which, in turn, resulted in a functional increase in their accumulation at an inflammatory reaction site. In conclusion, these studies indicated that the chemotactic activity of adoptively transferred cells can be modified by changes in the chemotactic stimuli, can be enhanced or depressed by serum factors, and is a function of the physiologic capability of the cell population employed.