Activation of neutrophils by a novel triggering immunoglobulin-like receptor MAIR-IV.

Neutrophils play a central role in host defenses against infectious microbial pathogens. However, molecular basis for their triggering signals has been incompletely understood. Here, we show molecular and functional characteristics of myeloid-associated immunoglobulin-like receptor (MAIR)-IV. MAIR-IV was preferentially expressed on neutrophils in the peripheral blood, bone marrow, peritoneal cavity and spleen. MAIR-IV physically associates with immunoreceptor tyrosine based activating motif (ITAM)-bearing adaptor FcRgamma chain. Cross-linking MAIR-IV with anti-MAIR-IV monoclonal antibody significantly induced secretion of proinflammatory cytokines TNF-alpha and IL-6 from neutrophils. Thus, MAIR-IV may regulate activation of neutrophils and play an important role for innate immunity.