MURINE NKG2D AND CD94 ARE CLUSTERED WITHIN THE NATURAL-KILLER COMPLEXAND ARE EXPRESSED INDEPENDENTLY IN NATURAL-KILLER-CELLS

Natural killer (NK) cells express C-type lectinlike receptors, encoded in the NK gene complex, that interact with major histocompatibility c omplex class I and either inhibit or activate functional activity. Hum an NX cells express heterodimers consisting of CD94 and NKG2 family mo lecules, whereas murine NK cells express homodimers belonging to the L y-49 family. The corresponding orthologues for other species, however, have not been described. In this report, we used probes derived from the expressed sequence tag database to clone C57BL/6-derived cDNAs hom ologous to human NKG2-D and CD94. Among normal tissues, murine NKG2-D and CD94 transcripts are highly expressed only in activated NK cells, including both Ly-49A(+) and Ly-49A(-) subpopulations. Additionally, m NKG2-D is expressed in murine NK cell clones KY-1 and KY-2, whereas mC D94 expression is observed only in KY-1 cells but not KY-2. Last, we h ave finely mapped the physical location of the Cd94 (centromeric) and Nkg2d (telomeric) genes between Cd69 and the Ly49 cluster in the NK co mplex. Thus, these data indicate the expanding complexity of the NK co mplex and the corresponding repertoire of C-type lectin like receptors on murine NK cells.