Influence of breast-feeding on the production of cytokines

PROBLEM: Recently, we reported increases in the production of interferon-ga mma (IFN-gamma), interleukin-2 (IL-2), and IL-4 during the postpartum perio d. The present study was undertaken to investigate whether these increases might be explained by increased prolactin while breast-feeding. METHOD: Whole blood from 41 women who were breast-feeding, 13 women not bre ast-feeding, and 31 healthy non-pregnant women was stimulated with phorbol 12-myristate 13-acetate and ionomycin, and the levels of cytokines in the s upernatant were measured by enzyme-linked immunosorbent assay. Their serum levels of prolactin were measured by enzyme immunoassay. RESULTS: Increases in IFN-gamma, IL-2, IL-4, and IL-10 production were obse rved in women who were breast-feeding but not in women who were not breast- feeding. Serum levels of prolactin correlated with the levels of IFN-gamma in culture supernatant. CONCLUSIONS: These results suggest that breast-feeding induces production o f cytokines and that IFN-gamma production is enhanced by physiological conc entrations of prolactin.