Mutation caused by human phagocytes.

Histidine-requiring mutants of Salmonella typhimurium TA100 were incubated with human peripheral blood leukocytes. More of these bacteria reverted to histidine independence than controls not incubated with cells. Phagocyte-rich suspensions were mutagenic, while heat-killed cells, lymphocytes, or mixed blood leukocytes of a patient with chronic granulomatous disease were not. Production of reactive oxygen metabolites could explain the capacity of phagocytes to induce mutation.