EFFECT OF EXERCISE ON MILK IMMUNOGLOBULIN-A

The major immunoglobulin (Tg) in human secretions is IgA. The immune p roperties of breast milk are well documented; however, the immunologic al influence of maximal exercise has not been established. The objecti ve of this study was to investigate the role that exercise has on brea st milk IgA and IgA subclasses. Breast milk was collected from 17 lact ating women (4.6 +/- 2.3 months postpartum) before and after randomize d exercise and control periods. The exercise treatment was a maximal g raded treadmill test ((V) over dot O-2max = 30.3 +/- 5.7 mL.min(-1).kg (-1)). Milk was collected at rest, the breasts were emptied, and sampl es obtained 10, 30, and 60 min following either exercise or 30-min con trol rest periods. IgA concentrations were established by enzyme-linke d immunosorbent assay, The results indicated that samples taken IO and 30 min after the exercise period had significantly lower (P less than or equal to 0.05) milli IgA concentrations (21.0 +/- 1.8 and 21.8 +/- 1.4 mu g mL(-1), respectively) than the corresponding control resting samples (52.8 +/- 3.5 and 79.3 +/- 7.7 mu g.mL(-1)). The exercise sam ples were similar to the control samples at 60 min (134.0 +/- 24.6 and 116.0 +/- 15.4 mu g.mL(-1), respectively), indicating that by I h, mi lk IgA production had recovered. The IgA1 data showed a similar signif icant decrease (P less than or equal to 0.05) al 10 min postexercise, which also returned to control concentrations by the 30- and 60-min co llection intervals, There was no significant change in the milk IgA2 c oncentrations at any of the time points studied. Milk IEA concentratio ns increased significantly in both exercise and resting control groups after the breasts were emptied, suggesting that breast emptying stimu lated milk IgA synthesis. The results provide evidence chat exercise a lters milk IEA and IgA1 concentrations for 10-30 min after exhaustive exercise, but recovers by I h, and provide additional support for exer cise effects on the mucosal immune system.