The Effect of Light, Moderate and Severe Bicycle Exercise on Lymphocyte Subsets, Natural and Lymphokine Activated Killer Cells, Lymphocyte Proliferative Response and Interleukin 2 Production

Abstract

The purpose of the present study was to evaluate the effect of acute bicycle exercise at different exercise intensities on the immune system. Six healthy volunteers exercised on a bicycle ergometer for 1 h at 25%, 50% and 75% of VO2max with an interval of 2 to 3 weeks. Blood samples were collected in the basal state, at the end of exercise and 2 h later. The absolute concentrations of all lymphocyte subsets increased during and fell after exercise at 50% and 75% of VO2max, but did not change significantly at 25% of VO2max. However, at all exercise levels, the percentage of CD3+ blood mononuclear cells decreased due to a decline in the fraction of CD4+ cells. This decline was most pronounced at 75% of VO2max. The fraction of NK cells expressing either the CD16 or the CD56 marker increased during exercise and declined to prevalues 2 h later, however the changes were most pronounced at 75% of VO2max. The natural killer (NK) cell and lymphokine activated killer (LAK) cell activities (lysis per fixed number of mononuclear cells) were increased during all exercise intensities, but were only suppressed below basal levels after exercise at 75% of VO2max. Indomethacin in vitro abolished the post-exercise suppression of NK cell activity and the proportion of CD14+ monocytes increased 2 h after exercise only at 75% of VO2max. These findings indicate that after exercise NK cell function is inhibited by prostaglandins released by monocytes. During exercise at 50% and 75% of VO2max the proliferative response of blood mononuclear cells (BMNC) following stimulation with phytohaemagglutinin A (PHA) decreased, whereas that following stimulation with interleukin-2 (IL-2) was enhanced. The IL-2 production by BMNC in vitro was markedly decreased during and after exercise at 75% of VO2max and this inhibition could be abolished by indomethacin in vitro. In conclusion, the response of the immune system to exercise depends on exercise intensity. In essence, the response is enhanced during exercise, however, after heavy exercise it is suppressed due to an increased level of prostaglandins produced by the elevated number of monocytes.

Attenuation of natural killer cell activity during 2-h exercise in individuals with spinal cord injuries

“…These results were similar to those described in previous studies. 4 Study limitation Subject numbers were marginal in the present experiment. However, several studies have examined exercise immunology in able-bodied subjects, and the subject numbers in some of these well-controlled studies were less than 10 persons.…”

“…However, several studies have examined exercise immunology in able-bodied subjects, and the subject numbers in some of these well-controlled studies were less than 10 persons. 4,6,15 Furthermore, it was difficult to recruit individuals with SCIs who met the strict inclusion criteria of the present study including completion of the 2-h arm crank ergometer exercise.…”

“…1,2 Severe or prolonged exercise suppresses immunological functions, while moderate or short-duration exercise activates immune functions. 3,4 Exercise in physically disabled persons contributes to the overall improvement of physical fitness and social interaction, and sports activities are highly recommended for individuals with spinal cord injury (SCI). It is widely known that persons with SCI easily develop infections of the urinary tract, respiratory tract and skin, because they seem to have weak host defense mechanisms.…”

Diferenças em populações de células exterminadoras naturais (Natural Killers-NK) sanguíneas periféricas entre atletas de caiaque e não atletas

“…They are rapidly recruit to the peripheral blood probably, via shear stress due to increase in blood flow added with a catecholamine--induced 20 down regulation of adhesion molecule expression. This increase in the peripheral pool has been associated with increased immune surveillance 21 .Despite of that, during prolonged exercise, circulating NK cells counting may decrease below the pre-exercise values 22 , in which the cells leave the peripheral blood circulation possibly to enter sites of muscle damage 23 . Cells exit from circulation or inhibition of their entrance may mean that these cells, especially the more cytotoxic subgroup, are extra or transiting to sites where they are needed for immune or inflammatory function.…”

Natural killer cells responsiveness to physical exercise: A brief review

“…Although many previous findings [12,14,15,[80][81][82][83] support the increase in circulating NK cell count during progressive exercise as well as the rapid post-exercise NK cell recovery, however, the experiment by Del Giacco et al [51] showed that the number of NK cells at the maximum workload did not further increase with respect to their number counted at VO 2-AT . This fact probably meant that when the contribution from anaerobic sources for exercising muscles became relevant (i.e.…”