Captopril enhances in vitro human lymphocyte thymidine incorporation

Angiotensin-converting enzyme activity is present in human sarcoid as well as murine schistosome granulomas. Inhibition of angiotensin-converting enzyme by captopril results in decreased granuloma size in animals. Since captopril is used clinically to treat hypertension, its effect on human lymphocyte thymidine incorporation was determined. It was found that 5 X 10(-5) M and 10(-4) M captopril enhances lymphocyte thymidine uptake induced by 25 micrograms/ml phytohaemagglutinin-P. This suggests that captopril can alter immunological reactivity in man and that angiotensin-converting enzyme may have an immunological function.