REGULATION OF MHC CLASS-I GENE-EXPRESSION IS AT TRANSCRIPTIONAL AND POSTTRANSCRIPTIONAL LEVEL IN BOVINE PLACENTA

A previous study of MHC in cattle trophoblast demonstrated low or abse nt class I expression, using a broad specificity monoclonal antibody. The study reported here uses MHC-defined cattle and embryo transfer to ensure MHC incompatibility between dam and calf. Transcription and ex pression of defined class I genes was examined in placentomes taken at term, using monoclonal antibodies to bovine class I, a gene-specific DNA-based typing system, and in situ hybridisation. Results demonstrat e intermediate levels of fetal MHC class I mRNA in trophoblast, but no detectable fetal class I protein. This suggests a level of transcript ional down-regulation, and a post-transcriptional block which might in volve other gene products, such as beta(2)-microglobulin (beta(2)m), o r proteins involved in generation/transport of peptides. (C) 1998 Else vier Science Ireland Ltd. All rights reserved.