Modulation of natural killer activity by thymosin alpha 1 and interferon

Abstract
A single injection of αβ-interferon (αβ-IFN) (30 000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals. We investigated the possibility of thymosin α1 cooperating with αβ-IFN in boosting NK activity in CY-suppressed animals. The results show that treatment with thymosin α1 (200 μg/kg) for 4 days, followed by a single injection of αβ-IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin α1 was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras. Taken together the data support the concept that the synergic effect between thymosin α1 and αβ-IFN could be the result of effects on differentiation of the NK lineage at different levels.