The leukocyte immunoglobulin-like receptors (LIRs): a new family of immuneregulators

Identification of a counterstructure for the human cytomegalovirus-encoded major histocompatibility complex class I-related gene product, UL18, has le d to the discovery of a novel family of immunoreceptors, termed leukocyte i mmunoglobulin-like receptors (LIRs). The LIRs are differentially expressed in cells of the dendritic cell, monocytic and lymphocytic lineages, and app ear to mediate diverse roles in immune regulation, This review summarizes t he expression, distribution, and signaling capacities of the LIRs and discu sses possible roles of the LIRs in both inhibition and activation of the ce llular responses.