LAIR-1, a Widely Distributed Human ITIM-Bearing Receptor on Hematopoietic Cells

In the last few decades, immunologists have mainly concentrated on the parameters that involve direct activation of the immune system. However, for the immune system to function properly, fine-tuned negative regulation of an immune response has now proven to be as important as appropriate activation. Failure of inhibitory mechanisms can lead to disastrous phenotypes, as witnessed by the lympho-proliferation in Fas−/−, FasL−/−, and CTLA4−/− mice; and the multi-focal inflammations in IL-10−/− and TGF-β−/− mice. Investigation of the inhibitory mechanisms of the immune system might lead to better insight in the mechanisms underlying autoimmune disease. Here, a novel inhibitory receptor, LAIR-1, is discussed. LAIR-1 has a broad cellular distribution in the immune system and thus might play a role in the regulation of a variety of immune responses.