Tissue distribution of the mRNA for a rhesus monkey major histocompatibility class Ib molecule, Mamu-AG

We identified recently a novel major histocompatibility complex (MHC) class I locus in the rhesus monkey, Mamu-AG, which is expressed in the placenta and encodes molecules that share unique characteristics of human HLA-G. We established locus specific reverse transcription-polymerase chair reaction (RT-PCR) and ribonuclease protection assays to determine whether Mamu-AG is expressed in other rhesus monkey tissues. With an RT-PCR assay, Mamu-AG mR NA was detected in placenta, amniotic membranes, kidney, spleen, eve, brain , lung spinal cord, liver and occasionally heart, but was undetectable in l ymph nudes, salivary glands, peripheral blood lymphocytes (PBL), large and small intestine, skeletal muscle or skin. Examination of endocrine organs d emonstrated the presence of Mamu-AG transcripts in pituitary, testes, ovary and adrenal glands but not in pancreas or thyroid. Quantitative analysis u sing a ribonuclease protection assay demonstrated that the highest level of Mamu-AG mRNA expression was consistently in the placenta and amniotic memb ranes, while expression was moderate in a few tissues (testis, adrenal) and low to undetectable in all other tissues. These results suggest that the M amu-AG mRNA, like the mRNA for the human MHC class Ib gene HLA-G, is expres sed at high levels in the placenta, but also has restricted low-level expre ssion in other tissues.