THE EFFECTS OF ACUTE MODERATE EXERCISE ON LYMPHOCYTE FUNCTION AND SERUM IMMUNOGLOBULIN LEVELS

The extent and duration of changes on lymphocyte function and serum immunoglobulin (Ig) levels were examined in 12 women who walked 45 min at 60% VO2max in a laboratory setting. A 2-factor, 2 x 6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest), and the second factor was time (six times of measurement over a 24-h period), with treatment order counterbalanced. The 45-min walk, in comparison to rest in a seated position, was not associated with significant changes in circulating numbers of interleukin-2-activated T cells (CD5 and CD25) or on spontaneous or concanavalin-A-stimulated lymphocyte proliferation. A trend for decreased phytohemagglutinin-stimulated lymphocyte proliferation in comparison to the rest condition, however, was seen 1.5 h following the exercise bout (p = 0.047). The patterns of change for serum IgG, IgA, and IgM were significantly different (p = 0.001, p < 0.001, p = 0.010, respectively) between conditions. IgG rose 7.2% immediately following exercise, and then returned to baseline 1.5 h later, which contrasted significantly with changes in the rest condition. These same patterns of change occurred also with IgA and IgM, but increases immediately following exercise were not significant, although a trend was seen for IgA (p = 0.03). The 45-min walk had no effect on plasma cortisol and epinephrine levels relative to the rest condition, but was associated with a significant 89% increase in norepinephrine. These data suggest that moderate exercise leads to a transient increase in serum immunoglobulin levels by way of contribution from extravascular pools and/or nonspecific stimulation of memory B cells. Antigen-dependent mechanisms do not appear to play a major role.