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

To examine the effect of exercise and adrenergic blockade on lymphocyte cytokine 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 bicycle exercise at 78 +/- 3% peak pulmonary uptake. Blood was collected before and after exercise, stimulated with phorbol 12-myristate 13-acetate and ionomycin, and surface stained for T (CD3(+)) and natural killer [NK (CD3(-)CD56(+))] 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 concentration 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- compared with preexercise. BLK attenuated (P < 0.05) the elevation in the concentration of lymphocytes producing cytokines during exercise; however, BLK did not affect the amount of IL-2 and IFN-gamma produced. These results suggest that adrenergic stimulation contributes to the exercise-induced increase in the concentration of lymphocytes in the circulation; however, it does not appear to be responsible for the exercise-induced suppression in cytokine production.