Conservation of a CD1 multigene family in the guinea pig

CD1 is a family of cell-surface molecules capable of presenting microbial l ipid Ags to specific T cells, Here we describe the CD1 gene family of the g uinea pig (Caria porcellus), Eight distinct cDNA clones corresponding to CD 1 transcripts were isolated from a guinea pig thymocyte cDNA library and co mpletely sequenced. The guinea pig CD1 proteins predicted by translation of the cDNAs included four that can be classified as homologues of human CD1b , three that were homologues of human CD1c, and a single CD1e homoloye. The se guinea pig CD1 protein sequences contain conserved amino acid residues s lid hydrophobic domains within the putative rig binding pocket. A mAb speci fic for human CD1b cross-reacted with multiple guinea pig CD1 isoforms, thu s allowing direct analysis of the structure and expression of at least a su bset of guinea pig CD1 proteins. Cell-surface expression of CD1 was detecte d on cortical thymocytes, dermal dendritic cells in the skin, follicular de ndritic cells of lymph nodes, and in the B cell regions within the lymph no des and spleen, CD1 proteins were also detected on a subset of PBMCs consis tent with expression on circulating B cells. This distribution of CD1 stain ing in guinea pig tissues was thus similar to that seen in other mammals, T hese data provide the foundation for the development of the guinea pig as a n animal model to study the in vivo function of CD1.