Neutrophil response to prolonged exercise in immune-competent and RAG2/gamma c null mice

The two aims of this study were (i) to compare the effects of prolonged exe rcise on circulating neutrophil number and muscle myeloperoxidase (MPO) act ivity between RAG2/gammac null and immune-competent mice, and (ii) to evalu ate the general suitability of the lymphocyte-deficient RAG2/gammac null st rain for use in exercise models of immune regulation. RAG2/gammac null (mal e and female) and C57BL/6 (congenic immune-competent, male) mice were assig ned to either control (C) or treadmill exercise (EX, 22 m/min, 90 min, 6% g rade) groups. EX mice were killed immediately (EX0) or 24 h (EX24) after ex ercise. RAG2/gammac null males had significantly (P < 0.05) fewer circulati ng CD45(+) cells and higher %CD45(+) neutrophils than did C57BL/6 males, in dependent of exercise. A significant interaction was observed for the effec ts of exercise and gender on %CD45(+) neutrophils in the blood. At EX24, ga strocnemius (Gastroc) MPO significantly increased in EX mice. Gastroc MPO a ctivity was 44% and 35% higher in RAG2/gammac null vs. C57BL/6 males, and i n female vs. male RAG2/gammac null mice, respectively. Heart MPO activity d id not differ between strains or among treatments. We concluded that the Ra g2/gammac null strain is a suitable model for future investigations on immu ne regulation following acute exercise stress.