Monoclonal antibody 1022-5 reacts with Allograft-inflammatory factor-1 (AIF-1) polypeptide, also known as Ionized calcium-binding adapter molecule 1, Iba-1. AIF-1 is a 17 kDa IFN-gamma inducible Ca2+-binding EF-hand protein, associated with chronic inflammatory processes. AIF-1 is constitutively expressed in lymphatic tissue and is up-regulated in monocytes/macrophages under various pathological conditions such as chronic rejection of allografts and in autoimmune lesions. In the brain, a subset of microglial cells constitutively express AIF-1. Increased numbers of AIF-1 immunoreactive macrophage/microglial cells were observed in focal brain infarctions, traumatic brain injury, gliomas, uveitis and in inflammatory lesions of a rat model of autoimmune disease, autoimmune encephalomyelitis and neuritis.Several Ca2+-binding peptides have been associated with monocyte activation, in particular members of the S-100 supergene-family. AIF-1 is a Ca2+-binding peptide which is not a member of the S-100 gene cluster but is located within the HLA class III genomic region.The monoclonal antibody 1022-5 is cross reactive with rat Allograft-inflammatory factor-1 (rat AIF-1). Human and rat amino acids sequences are 98% homologous.