N-linked carbohydrate on human leukocyte antigen-C and recognition by natural killer cell inhibitory receptors

The possible role of carbohydrate in the interaction of HLA-C with a human inhibitory natural Killer cell Immunoglobulin-like Receptor with two Ib dom ains, KIR2DL1, was investigated. Transfectants of 721.221 (a class I MHC-ne gative human B cell line) expressing only HLA-Cw4 or -Cw6 or their respecti ve non-glycosylated mutants (N86Q, S88A) were made. The binding of a KIR2DL 1-Ig fusion protein to the non-glycosylated mutant HLA-Cw4- or -Cw6-express ing cells was markedly decreased compared to the wild type-expressing cells . The ability to induce an inhibitory signal in the NK tumor line YTS trans fected with KIR2DL1 was also impaired in the nonglycosylated mutant express ing cells. Furthermore, in a second functional assay, mutant HLA-Cw I and - Cw6 molecules had impaired ability to induce signal transduction in BW cell s expressing a KIR2DL1-CD3 zeta chain chimeric protein. Thus, the deletion of the N-linked glycosylation signal in HLA-Cw4 and -Cw6 greatly reduced re cognition by KIR2DL1. Alternative interpretations of the data are discussed . (C) American Society for Histocompatibility and Immunogenetics, 2000. Pub lished by Elsevier Science Inc.