TAP-INDEPENDENT, BETA(2)-MICROGLOBULIN-DEPENDENT SURFACE EXPRESSION OF FUNCTIONAL-MOUSE CD1.1

CD1 molecules consist of beta(2)-microglobulin (beta(2)m) noncovalently complexed to a non-major histocompatibility complex (MHC)-encoded monomorphic integral membrane protein homologous to MHC class I alpha chains. Little is known about the requirements for cell surface expression and T cell recognition of CD1. We inserted the mouse CD1.1 gene into vaccinia virus to create a recombinant virus expressing CD1.1 under the control of a viral promoter. Using this recombinant virus to infect normal or mutant cell lines, we found that the expression of molecules reactive with the CD1.1-specific monoclonal antibody 3C11 requires the expression of beta(2)m but was not affected by the absence of the MHC-encoded peptide transporter (TAP). Consistent with these results, IL-2 production by the mCD1.1-specific T cell hybridoma DN32.D3 was induced by thymocytes from normal mice or mice with a homozygous deletion of the TAP1 gene, but not by thymocytes from mice with a homozygous deletion of the beta(2)m gene. These results indicate that expression of functional mCD1.1 occurs in a beta(2)m-dependent, TAP-independent manner.