Description: The monoclonal antibody N11 reacts specifically with the 77 amino acid form of IL-8 (IL-877, IL-8(1-77), CXCL877) and does not react with the more common 72 amino acid form. Frequently referred to as “endothelial” IL-8, the 77 amino acid form is secreted in cultured leukocytes. The 72 amino acid form is the result of efficient cleavage of an N-terminal pentamer from IL-877 after secretion. IL-8 is a C-X-C chemokine with potency in neutrophil chemotaxis and activation. IL-877 has decreased chemotactic activity when compared to IL-872, but has other specific pro-apoptotic and tumor cell chemotactic activities. IL-877 has recently been shown to be the major isoform present in premature neonates due to deficiency in serum protease activity that is not seen in term neonates.