The monoclonal antibody 6B1 recognizes human triggering receptor expressed on myeloid cells 1 (TREM-1). TREM-1 is a transmembrane glycoprotein belonging to a family related to the natural killer cell receptors. TREM-1 is an important activating receptor, of 26 kDa, involved in the innate inflammatory response and in sepsis. TREM-1 is expressed at low levels in the early development of the hematopoietic system and in the promonoistic stage and at high levels on neutrophil granulocytes (PMN), monocytes, and macrophage subsets. The expression of TREM-1 is upregulated by microbial products, that is, by toll-like receptor ligands such as lipoteichoic acid (LTA) of Gram-positive or lipopolysaccharide (LPS) of Gram-negative bacteria. Ligation of TREM-1 is synergistic with TLR agonists on the activation of receptor bearing cells. Platelets express a natural ligand for TREM-1. Receptor ligation activates the full repertoire of effector functions.TREM-1 is also produced in a soluble form (sTREM-1) of 17 kDa which is released in humans after endotoxin exposition or in patients suffering from severe pneumonia or sepsis. sTREM-1 can be measured in biological fluids and may be useful as a diagnostic tool. The monoclonal antibody 6B1 recognizes both membrane bound and soluble TREM-1.Also, the monoclonal antibody 6B1 neutralizes the interaction between TREM-1 and its ligand.