Cell-mediated immunity in vasectomized rhesus monkeys.

Cell-mediated immunity in rhesus monkeys that had been vasectomized for 2, 4, 7, or 11 years was measured by lymphocyte blastogenesis following stimulation with concanavalin A, phytohemagglutinin (PHA), and pokeweed mitogens. Several of the 7- and 11-year vasectomized animals had significantly reduced PHA reactivity when compared with control animals, and the percentage of animals with reduced PHA reactivity increased with time after vasectomy.