ASPECTS OF LEUKOCYTE FUNCTION AND THE COMPLEMENT-SYSTEM FOLLOWING AEROBIC EXERCISE IN YOUNG FEMALE GYMNASTS

Recent studies have reported reduced immunity in trained athletes. Sca nt information exists on changes in the immune function among trained children. The purpose of this study was to assess the effect of aerobi c exercise on the phagocytic process of neutrophils and the complement system in young athletes. Subjects included prepubertal elite female gymnasts (n=7) and untrained girls (n=6) aged 10-12 years. Venous bloo d was withdrawn before, immediately post and 24 h following a 20-min r un at a heart rate of 170-180 beats.min(-1). Neutrophil random migrati on, chemotactic activity, bactericidal function and PMA/FMLP-stimulate d superoxide anion release as well as various complement components we re assessed. Net chemotaxis was found reduced (P<0.05) 24 h following exercise (58+/-11 vs. 36+/-11 cells/field in gymnasts and 47+/-7 vs. 4 2+/-8 cells/field in untrained girls pre-and 24 h post-exercise, respe ctively). The basal values, as well as post-exercise values of bacteri cidal activity were lower (P<0.05) in gymnasts as compared with the co ntrol group (0.8+/-0.3, 0.8+/-0.2 and 0.8+/-0.1 log decrease of coloni es in gymnasts at pre-, immediately post-, and 24 h post-exercise, res pectively and 1.1+/-0.1, 1.1+/-0.1 and 1.0+/-0.2 log decrease of colon ies in controls, respectively). No significant effect on the bacterici dal activity was observed in either group following exercise. The addi tion of homologous sera did not correct the bactericidal activity. PMA -stimulated superoxide anion release decreased (P<0.05) among gymnasts immediately following exercise (5.7+/-0.4 vs. 4.4+/-1.0 mmol O-2/10(6 ) PMN.min) and remained low 24 h later. The same trend was observed in FMLP-stimulated neutrophils but the data were not significant. Signif icantly decreased levels (P<0.05) of the early complement components ( C1Q, C1R) were also found following exercise (1.34+/-0.64 vs. 1.27+/-0 .28 and 1.09+/-0.07 vs. 1.02+/-0.06 pre-and postexercise in gymnasts a nd untrained, respectively). Furthermore, consistently lower C2 and C3 were observed in gymnasts compared with controls. Neutrophil dysfunct ion as well as impairment of the complement system seem to occur follo wing exercise.