Direct binding of purified HLA class I antigens by soluble NKG2/CD94 C-type lectins from natural killer cells.

Division of Clinical Immunology, Karolinska Institutet, Huddinge University Hospital, Huddinge, Sweden.

Human natural killer (NK) cell cytotoxicity is inhibited following human leucocyte antigen (HLA) class I binding by killer cell inhibitory receptors belonging to the immunoglobulin or C-type lectin protein families. Of the latter family, CD94 and NKG2A or -B associate to inhibit NK cell cytotoxicity. We have constructed C-Myc epitope-tagged soluble NKG2A, -B, -C, -D and human NKR-P1 lectin domains, and studied their ability to associate with Flu-tagged soluble CD94 lectin domains. Furthermore, their ability to bind solubilized immunoaffinity-purified HLA class I antigens, either alone or following association with CD94 lectin domains, was evaluated using flow cytometry and Western blot analyses. We show that soluble NKG2A, -B and -C lectin domains interact with CD94 lectin domains to form complexes, whereas NKG2D and human NKR-P1 lectin domains do not. Soluble NKG2C, -D and CD94 lectin domains bind solubilized affinity purified HLA class I antigens on their own, whereas NKG2A and -B require association with CD94 lectin domains for binding. Soluble human NKR-P1 lectin domains do not bind solubilized HLA class I antigens in our system.

PMID: 10320637 [PubMed - indexed for MEDLINE]