Response of human peripheral blood lymphocytes in the presence of cord sera: relationship of lymphocyte transformation with number of pregnancies and levels of alpha-fetoprotein.

Peripheral blood lymphocytes were stimulated with various mitogens (PHA, Con A and PWM) and allogenic cells in the presence of cord serum. The cord sera suppressed more effectively certain T cell populations. This immunoregulatory response of cord serum was compared with nonpregnant and pregnant sera from different gestations. Although the cord sera showed significantly higher inhibition compared to normal adult serum but the serum from gravidae in late gestation proved more inhibitory compared to cord serum. No correlation was found between the levels of alpha-fetoprotein (AFP) in the cord sera and the degree of inhibition observed in the cultures. As previously described for pregnant sera the cord serum obtained from women with different numbers of pregnancies did not correlate with the inhibition of cellular proliferation. Our results suggest a possible different suppressor factor in pregnant and cord sera and also excludes the possibility of AFP in cord sera as a suppressor agent of cell-mediated immunity.