n International SportMed Journal - An alternate approach to assessing immune function related to upper respiratory tract infection (URTI) : review article

Volume 4, Issue 3
  • ISSN : 1528-3356



An increased incidence of upper respiratory tract infection (URTI) has been associated with acute, prolonged bouts of strenuous of exercise, as well as with strenuous training and overtraining syndrome. It has been assumed that the increased incidence of infection is associated with high volume/intensity training, resulting in immunosuppression. Although many aspects of immune function have been monitored, no cohesive pattern concerning alterations in immune function has emerged. The purpose of the present paper is to propose that the recent understanding of the dichotomy of T-helper (Thp) precursor lymphocytes into Th1- and Th2-effector lymphocytes may be applied to this field of research to provide a comprehensive explanation of alterations that may occur in response to strenuous exercise and the increased incidence of URTI. The dichotomy of Th-lymphocytes into Th1- or Th2- lymphocytes is dependent on the prevailing cytokine pattern. Interleukin (IL)-6 and IL-4 drives Tp-lymphocytes to a Th2/humoral response (HI), while IL-12 and interferon (IFN)γ drives Tp-lymphocytes to a Th1/cell mediated (CMI) response. The up-regulation of Th2/HI results in suppression of Th1/CMI, which would place the athlete at risk for URTI. Information gleaned from several exercise studies is suggestive of a post-exercise Th 2-lymphocyte response, with elevated levels of IL-6, IL-10 and IL-4, and an absence of type 1 cytokines (IL-12 and IFNγ ). The scenario of increased HI and suppressed CMI would provide an explanation for increased incidence of URTI after strenuous exercise. Recommendations are made to examine this postulate.

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