Serum-soluble human leucocyte antigen class I and class II concentrations as an alternative diagnostic test for determining immune indices required for normal pregnancies

Abstract

The levels of maternal immunostimulation (required throughout the gestation period) and immunosuppression (needed from the 8th week to labour), as assessed by the mixed lymphocyte reaction (MLR), have been successfully correlated with the outcome of pregnancy. Our laboratory has recently reported that serum-soluble human leucocyte antigen (HLA) class I and II concentrations can be predictive for successful pregnancy outcome. In fact, there is a direct correlation between soluble class II concentrations and maternal immunostimulation because, as expected, these serum HLA concentrations are augmented in the first and second trimester of pregnancy and remain stable thereafter. By the same token, serum HLA class I concentrations are low during the first trimester, correlating with the required absence of immunosuppression, whereas they increase in subsequent trimesters as suppression becomes desirable for counteracting the maternal stimulation, which may otherwise become dangerous to the fetus. In this study, we present biological and statistical evidence that both states of maternal immunostimulation and immunosuppression, reflected by serum soluble HLA class II and class I antigens, do correlate with results obtained by standard MLR and can be predictive of pregnancy failure. The establishment of statistically significant correlations renders the measurement of soluble HLA a reliable test for determining the immunological status of the gestating woman. The unambiguous advantage of such an approach is that soluble HLA testing will no longer require the 1 week delay necessary to obtain MLR results, a period occasionally crucial for applying treatment to women whose immunological indices call for immediate therapeutic intervention.