ENHANCED EXPRESSION OF HLA-DR, FC-GAMMA RECEPTOR-1 (CD64) AND LEUKOCYTE COMMON ANTIGEN (CD45) INDICATE ACTIVATION OF MONOCYTES IN REGENERATIVE TRAINING PERIODS OF ENDURANCE ATHLETES

The aim of this study was to test the hypothesis whether endurance ath letes have distinct expressions of functionally relevant surface antig ens of monocytes, Under standardized experimental and laboratory condi tions CD14(+) blood monocytes of 55 males (22 sedentary controls [CO], individual anaerobic threshold [IAT]: 2.2 +/- 1.2 W . kg(-1), VO(2)ma x: 47 +/- 12 ml . min(-1) . kg(-1); 13 endurance athletes, training: 3 -10 hours weekly [E(1)], IAT: 3.0 +/- 1.1 W . kg(-1) VO(2)max: 57 +/- 5 ml . min(-1) . kg(-1): 20 endurance athletes training: >10 hours wee kly [E(2)], IAT: 3.7 +/- 1.3 W . kg(-1), VO(2)max: 64 +/- 6 ml . min(- 1) . kg(-1)) were investigated for relative surface receptor expressio n of CD45, CD64 and HLA-DR (direct immunofluorescence, flow cytometry) . E(1) and E(2) showed significantly (ANOVA, Tukey's HSD test; each p < 0.01) higher relative receptor expressions for CD64 in comparison to CO (E(1): + 62/E(2): + 71%: percentage of increase compared to CO val ue), CD45 (+ 44/+ 31%) and HLA-DR (+ 22/+ 35%), Cell counts of four mo nocyte subpopulations (CD56(+), CD14(bright+)CD16(-), CD14(bright+)CD1 6(dim+), CD14(dim+)-CD16(bright+)) did not show significant difference s between the groups. These data suggest that in endurance athletes du ring regenerative training period circulating monocytes show an enhanc ement of functionally relevant surface receptors indicating an activat ion of monocytes.