Lymphocyte subpopulations in lymphoid organs of rats after acute resistance exercise

Purpose: The ability of aerobic exercise to change lymphocyte subpopulation distributions is well documented; much less is known about resistance exer cise. The purpose of this experiment was to determine the effects of an acu te bout of resistance exercise on lymphocyte subpopulations in primary and secondary lymphoid compartments, Methods: Male rats were operantly conditio ned to climb a ladder while carrying weights that were progressively increa sed to equal body weight. During the acute session, rats performed repetiti ve climbs until exhaustion. Thymus, spleen, blood and axial and inguinal ly mph nodes were removed; leukocytes were isolated and incubated with monoclo nal antibodies against differentiation markers, activation antigens, and ad hesion molecules. Results: Exercised versus control rats had greater number s of leukocytes in the thymus, axial, and inguinal nodes but not in the blo od or spleen. The percentage of CD4(+) cells increased after exercise in th e thymus, spleen, and blood. The percentages of cells expressing the integr in LFA-1 beta were elevated in all the tissues except inguinal lymph nodes. In addition, more leukocytes from exercised than nonexercised rats express ed detectable numbers of activation markers, IL-2 receptor-alpha and MHC cl ass II molecules; however, as indicated by proliferating cell nuclear antig en analysis, the cells were not actively dividing at the time of assay. Con clusions: Based on these and published data, it appears that a single bout of resistance exercise can affect lymphoid cell subpopulations probably by inducing changes in leukocyte trafficking.