Puberty effects on NK cell responses to exercise and carbohydrate intake in boys

Purpose: To determine whether the smaller perturbations in NK cells induced by strenuous exercise and carbohydrate (CHO) intake, previously reported in children, are influenced by puberty. Methods: Twenty 12-yr-old boys, distinguished as prepubertal (Tanner (T) 1, N = 7), early pubertal (T2, N = 7), or pubertal (T3-5, N = 6), cycled for 60 min at 70% VO2max while drinking 6% CHO (CT) or flavored water (WT). Blood was collected at rest and (luring (30 and 60 min) and following (30 and 60 min) exercise to identify NK cells as CD3(-)CD56(dim) or CD3(-)CD56(bright). CD69 expression on CD3(-)CD56(+) cells was also determined. Results: A puberty x CHO x exercise interaction was found for the proportion, but not number, of CD56(dim) cells (P = 0.06). CD56(dim) cell counts were lower in CT versus WT (P < 0.00 1). Responses of CD56(bright) proportions (P = 0.007) and counts (P = 0.03) depended on pubertal status, but not CHO. The CD56(bright):CD56(dim) ratio remained stable during exercise, but during recovery was higher in TI and T3-5 versus T2 (P = 0.08) and in CT versus WT (P = 0.04). During recovery, CD3(-)CD56(+) cells expressed higher levels of CD69 (P = 0.01), with no change in the proportion of CD69(+) cells. Conclusion: These results confirm the influence of puberty on the distribution of NK cell subsets in response to exercise and CHO intake. Increased CD69 expression suggests that NK cells increase activation status during recovery from physiological stress.