Reduced T cell reactivity in vasectomized rhesus monkeys: association with histocompatibility type.

The capacity of peripheral lymphocytes from rhesus monkeys which had been vasectomized for 7 or 11 years to stimulate and respond to normal rhesus lymphocytes in mixed lymphocyte cultures (MLC) was tested to determine whether vasectomy affects immunologic reactivity. The ability to respond in MLC, a T cell function, was significantly reduced in the 11-year vasectomized animals and in two 7-year vasectomized animals. The ability to stimulate in MLC, a B cell function, was significantly increased in the 11-year vasectomized group. MLC reactivity of normal lymphocytes cultured in plasma from vasectomized animals and lymphocytes from vasectomized animals cultured in normal plasma was not altered, ruling out serum effects in the reduction of MLC responsiveness in these vasectomized animals. Seventy-five per cent of the vasectomized animals with markedly reduced MLC reactivity had the RhL-A determinates 19 and 24, indicating an association between the tendency toward reduced MLC reactivity after vasectomy and histocompatibility type.