Porcine CD1 is a type I transmembrane glycoprotein and a member of the immunoglobulin superfamily of cell surface receptors. It has a domain organization similar to that of MHC class I molecules and is expressed in association with beta2-microglobulin. CD1 is found on B cells, macrophages, and immature thymocytes. There is evidence for a role of CD1 in presentation of lipids and peptides to T cells.