In vitro enhancement of natural cytotoxicity by atrial natriuretic peptide fragment 4-28

The presence of atrial natriuretic peptide (ANP) binding sites in the thymic cortex, medulla, and splenic white pulp suggests that this peptide may have immunoregulatory activity. We examined the effect of ANP on human natural killer (NK) cell activity. ANP significantly augmented NK cell cytotoxicity after twenty-four hours of incubation but had no effect on NK activity after short-term incubations of one hour. In addition, atrial natriuretic peptide did not effect the expression of natural killer or T cell surface markers. This study demonstrates that atrial natriuretic fragment 4-28 enhances natural killer cell activity.