Lectin-based analysis of fucose and sialic acid expressions on human amniotic IgA during normal pregnancy

The sugar moiety of IgA is known to provide a link between the innate and adaptive immune systems. Terminally located glycotopes on IgA are potential ligands engaged in the interactions which may modulate the biological activities of IgA. In the present work the expressions of Maackia amurensis (MAA), Sambucus nigra (SNA), Lens culinaris (LCA), Tetragonolobus purpureus (LTA), and Ulex europaeus (UEA) reactive glycotopes on maternal plasma and amniotic IgA were evaluated in relation to the progression of a normal human pregnancy, from the 2nd trimester, throughout the 3rd trimester, perinatal period, post-date pregnancy and delivery, by lectin-IgA-ELISA, using specific biotinylated lectins. The amniotic and maternal plasma IgA concentrations and a degree of SNA and LCA reactivity of maternal plasma IgA were almost unaltered during the normal pregnancy. The amniotic IgA from the 2nd trimester was decorated by MAA-, SNA-reactive and LCA-, LTA-, and UEA-reactive glycotopes. At the turn of the 2nd and 3rd trimesters the expression of MAA-, SNA-, LTA-, and UEA-reactive glycotopes, except for LCA-reactive, increased and remained almost at unaltered levels throughout the perinatal period and delivery. However, in the post-date pregnancy the expression of LCA-, LTA-, and UEA-reactive and SNA-reactive glycotopes were significantly higher. The unique fucosylated and sialylated glycovariants of amniotic IgA associated with the progression of the normal pregnancy may illustrate a general importance of carbohydrate-lectin receptor interactions in the control and modulation of biological events to ensuring homeostasis during pregnancy, protection and well-being of fetus.