Inhibition of lymphocyte transformation by serum from pregnant women: lack of correlation with levels of alpha-fetoprotein.

Lymphocytes from pregnant and non-pregnant women were stimulated with optimal doses of phytohaemagglutinin (PHA) in order to detect any possible suppression of the maternal cellular immune capabilities. No major differences were observed. Similar cultures using lymphocytes from normal healthy individuals were exposed to sera from pregnant and non-pregnant women. A consistent inhibitory influence, more pronounced at the end of gestation, was identified in the sera from pregnant women. No correlation was found between the levels of alpha-fetoprotein in the pregnant sera and the degree of inhibition observed in the cultures.