Chronic Effect of Training on Neutrophil Functions in Humans

We performed this study to evaluate the chronic effect of training on neutrophil functions in humans. Twenty-six university students (14 males and 12 females) with a mean age of 19.1±0.8 years were divided into the athlete group and the control group based on answers given to a written questionnaire. The capacity of circulating neutrophils to ingest bacteria (phagocytosis) and to produce superoxide (nitroblue tetrazolium reduction) was measured under resting conditions in the absence of training activities. In addition, we measured hematological and serum biochemical parameters. The present analyses revealed that the frequency of subjective symptoms concerning susceptibility to infections (sum of males and females) was higher in the athlete group than in the control group (p<0.05). In the investigation of males, hemoglobin and serum protein levels of the athlete group were lower than that of the control group (p<0.01, p<0.05, respectively). Although total and differential leukocyte counts, and phagocytic activity of neutrophils were not significantly different between the groups, superoxide productivity of neutrophils in the male athlete group was higher than that in the control group (p<0.05). Since significant differences were observed in hemoglobin and serum protein levels in the male athletes, the training is considered to have been intense. An increase was noted in the neutrophil superoxide production along with these changes, but no significant difference was observed in the phagocytic activity. Therefore, there is the possibility of superoxide overproduction, which may lead to tissue damage.

Chronic effects of voluntary exercise on SRBC-induced host defense reactions in rats / 体力科学

A study was conducted to evaluate the chronic effects of regular physical activity on nonspecific and specific immune responses. Male Fischer rats (SPF) exercised voluntarily on running wheels for 4 months, and were then injected intraperitoneally with sheep red blood cells (SRBC), followed by measurement of the host defense functions at -2 d, 3h, 24h and 4 d of antigen stimulation. The following results were obtained:<BR>1) The ability of circulating neutrophils to produce superoxide measured by the spontaneous NBT test showed an earlier and higher (p<0.05) rise after SRBC injection in the exercise group, suggesting that neutrophils were activated <I>in vivo</I> more promptly against foreign-body invasion. This might reflect a priming response of neutrophils at the early phase of SRBC-induced host defense reactions modulated by the previous regular exercise.<BR>2) The ability of neutrophils to produce superoxide in response to <I>in vitro</I> stimulation with <I>Staphylococcus aureus</I> 209 P was markedly reduced during inflammatory response in the sedentary group, whereas that in the exercise group was maintained at a constant level. The value at 4 d after SRBC injection in the sedentary group was decreased to more than 20% below the baseline (p<0.02) . In addition, a significantly (p<0.02) lower value than that in the exercise group was shown, although phagocytic activity was similar in the two groups. This suggested that neutrophil bactericidal activity was decreased in the sedentary group.<BR>3) Plasma IgG levels in the exercise group were consistently and significantly (p<0.0001) higher by about 30% than those in the sedentary group, regardless of SRBC injection. This suggested an enhanced host defense status by regular exercise.<BR>4) The specific humoral immune response to SRBC injection was assessed in terms of hemagglutination and plasma IgM levels, but no significant differences were shown between the groups.