Relationship between serum immunoglobulin G and alpha-fetoprotein levels during human pregnancy.

The immunoregulatory processes operating during pregnancy that allow the survival of the semiallogeneic conceptus are at present far from understood. alpha-fetoprotein (AFP) is a biological component of the body produced in high amounts during pregnancy mainly by the fetal liver, and in certain clinical pathological states. The biological function of AFP is still unknown, but some investigators postulate an immunosuppressive role for the protein during pregnancy. In this study, serum immunoglobulin G, M and A levels of 101 gravidas at different stages of gestation (26 from 11-14 weeks, 37 from 32-34 weeks and finally 38 from 38-40 weeks) were determined and compared to 57 age matched nonpregnant females. Before being included in the study, patients were checked for various conditions which potentially alter immunoglobulin and AFP serum levels. Maternal serum samples showed a significant decreased concentration of immunoglobulin G (IgG) as compared to non-pregnancy serum samples (table I). AFP levels were also quantitated in the pregnancy sera and correlated with immunoglobulins levels. A strongly negative correlation between AFP and IgG was found throughout gestation (table II). When gestational age was fixed and the partial coefficients of correlation calculated, the inverse correlation persisted. In addition, the relationship between AFP and IgG at the various periods of gestation (11-14 weeks, 32-34 weeks and 38-40 weeks), calculated in order to detect where the association was stronger, revealed significant and uniform negative correlations (table III).(ABSTRACT TRUNCATED AT 250 WORDS)