SOME ASPECTS OF THE ACUTE-PHASE RESPONSE AFTER A MARATHON RACE, AND THE EFFECTS OF GLUTAMINE SUPPLEMENTATION

Strenuous exercise may be associated with immune suppression. However, the underlying mechanism is not known. A decrease in the plasma level of glutamine, which is utilised at a high rate by cells of the immune system, and an increase in the plasma level of some cytokines may imp air immune functions such as lymphocyte proliferation after prolonged, exhaustive exercise. In two separate studies of the Brussels marathon , using similar protocols, the time course of the changes in the plasm a concentrations of some amino acids (glutamine, glutamate, alanine, t ryptophan and branched chain amino acids), acute phase proteins and cy tokines (interleukins IL-1 alpha, IL-2, IL-6, tumour necrosis factor t ype a) was measured in male athletes. The numbers of circulating leuco cytes and lymphocytes were also measured. Amino acid and cytokine conc entrations have not previously been measured concomitantly in marathon runners; the measurement of some of these parameters the morning afte r the marathon (16 h) is novel. Another novel feature is the provision of glutamine versus placebo to marathon runners participating in the second study. In both studies the plasma concentrations of glutamine, alanine and branched chain amino acids were decreased immediately afte r and Ih after the marathon. Plasma concentrations of all amino acids returned to pre-exercise levels by 16 h after exercise. The plasma con centration of the complement anaphylotoxin C5a increased to abnormal l evels after the marathon, presumably due to tissue damage activating t he complement system. There was also an increase in plasma C-reactive protein 16 h after the marathon. The plasma levels of IL-1 alpha were unaffected by the exercise, while that of IL-2 was increased 16 h afte r exercise. Plasma IL-6 was increased markedly (approximate to 45-fold ) immediately after and at 1 h after exercise. Neopterine, a macrophag e activation marker, was significantly increased post-exercise. There was a marked leucocytosis immediately after the marathon, which return ed to normal 16 h later. At the same time there was a decrease in the number of T-lymphocytes, which was further reduced within 1 h to below pre-exercise levels. Glutamine supplementation, as administered in th e second study, did not appear to have an effect upon lymphocyte distr ibution.