Expression of CD1D mRNA transcripts in human choriocarcinoma cell lines and placentally derived trophoblast cells

Human placental trophoblast is critically involved in mediating maternal to lerance of the fetal semiallograft. Genes encoding highly polymorphic major histocompatibility complex (MHC) class I and class II antigens that could provoke maternal immune rejection responses are silenced in trophoblast. Ho wever, several MHC class I or class I-related products exhibiting reduced o r negligible polymorphism are expressed and assumed to be functionally invo lved in maintaining pregnancy. The CD1 gene Family encodes non-polymorphic MHC class I-like products that have the unusual ability to present non-pept ide antigens to T cells. One member, CD1D, is expressed in certain epitheli al cells and interacts with a specific T-cell subset that may promote the d evelopment of Th2-mediated responses believed to be associated with pregnan cy. In this study we examined the expression of CD1D in human trophoblast c ell lines and placentally derived trophoblast cells by reverse transcriptas e-polymerase chain reaction using CD1D-specific oligonucleotide primers. We have found that CD1D mRNA transcripts are expressed in trophoblast cells a nd cell lines. We have also identified a novel alternatively spliced CD1D m RNA transcript lacking exon 4. Exon 4-intact and exon 4-deficient CD1D tran scripts appear to be differentially expressed in different trophoblast and non-trophoblast cell populations. Our studies suggest that at least one mem ber of the CD1 family is transcribed in human trophoblast.