INCREASED CD45RA(-CELLS AFTER ENDURANCE EXERCISE()CD45RO(+) CELLS INDICATE ACTIVATED T)

Twelve endurance athletes performed either a 240-km cycle race in the Alps or an ultratriathlon (time: 731 +/- 25 min). Two weeks before (S1 ) and on the 8th or 9th day after (S2) the competition, an exhaustive exercise at 110% of the individual anaerobic threshold was performed ( stress test; S1: 21 +/- 2 min; S2: 18 +/- 2 min). Blood samples at res t, at 10 min, at end, and 60 min after S1 or S2 were taken for immunop henotyping of leukocytes with fluorescein- or phycoerythrin-conjugated monoclonal antibodies (CD3, CD4, CD8, CD14, CD16, CD45, CD45RO, CD45R A, CD69, HLA-DR) and dual color flow cytometry. Of the lymphocyte subp opulations, the CD45RO+-lymphocytes had higher cell numbers at S2 than at S1 (P < 0.0 1). This was due to the increase of CD45RA+CD45RO+ lym phocytes (P < 0.005), but not to the CD45RA-CD45RO+ lymphocytes (P > 0 .05). Both the CD4+ (+39%) and CD8+ (+75%) cells were increased at S2. The activation markers CD69 and HLA-DR were not significantly increas ed at S2. Our conclusion is that a approximately 12h endurance exercis e induces activation of T-cells, which is indicated by the increase of CD45RA+CD45RO+. This might also indicate an increase of memory cells by prolonged endurance exercise.