Natural killer cell receptors specific for major histocompatibility complex class I molecules.

in some cases, suggesting that the Ly-49family memberscould also behave as ac-tivation receptors (54). Detailed analysisofthespecificity ofLy-49familymembersshouldimproveourunderstanding ofNKcell specificity.In humans, activation receptors haveyet to be identified. However, substantialprogresshasbeenmadeonthefunctionofputative inhibitory receptors specific forHLAclass I molecules. Moretta andcol-leagues (55-57) have shown that mAbsGL183 and EB6 react with serologicallydistinct epitopes on molecules, termedp58, on human NKcells. Either epitopemay be expressed on 55-kDa or 58-kDamonomersoronnoncovalentlylinkedhet-erodimers