Effect of adrenergic blockade on lymphocyte cytokine production at rest and during exercise

To examine the effect of exercise and adrenergic blockade on lymphocyte cyt okine production, six men ingested either a placebo (control) or an alpha- (prazosin hydrochloride) and beta -adrenoceptor antagonist (timolol malate) capsule (blockade, or BLK) 2 h before performing 19 +/-1 min of supine bic ycle exercise at 78 +/-3% peak pulmonary uptake. Blood was collected before and after exercise, stimulated with phorbol 12-myristate 13-acetate and io nomycin, and surface stained for T (CD3(+)) and natural killer [NK (CD3(-)C D56(+))] lymphocyte surface antigens. Cells were permeabilized, stained for the intracellular cytokines interleukin (IL)-2 and interferon (IFN)-gamma, and analyzed using flow cytometry. BLK had no effect on the resting concen tration of stimulated cytokine-positive T and NK lymphocytes or the amount of cytokine they were producing. Exercise resulted in an increase (P<0.05) in the concentration of stimulated T and NK lymphocytes producing cytokines in the circulation, but these cells produced less (P<0.05) cytokine post-c ompared with preexercise. BLK attenuated (P<0.05) the elevation in the conc entration of lymphocytes producing cytokines during exercise; however, BLK did not affect the amount of IL-2 and IFN-<gamma> produced. These results s uggest that adrenergic stimulation contributes to the exercise-induced incr ease in the concentration of lymphocytes in the circulation; however, it do es not appear to be responsible for the exercise-induced suppression in cyt okine production.