High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii

The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal–fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p < 0.001). Moreover sHLA-G level from congenitally infected fetuses (n = 12) was higher than in fetus in whom congenital infection was ruled out (n = 49, p < 0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.