Human allograft inflammatory factor 1 (AIF 1) is also referred as ionized calcium- binding adapter molecule 1 and is coded by gene AIF 1. The gene is situated within the major histocompatibility complex segment of class III region. This gene is greatly expressed in spleen and testis along with weak expression in lung, kidney and brain. The human allograft inflammatory factor 1 protein is located in the cytoplasm and is highly conserved. Allograft inflammatory factor-1 was first discovered in rat model of chronic allograft cardiac rejection with atherosclerotic lesions. Allograft inflammatory factor 1 is upregulated in response to cytokine IFN-Gamma in macrophages and neutrophils. Arterial injury leads to Allograft inflammatory factor 1 expression. Allograft inflammatory factor 1 enhances growth and promotes proliferation in vascular smooth muscle cells via alteration in the regulation of cell cycle. Allograft inflammatory factor 1 also interacts with p44/42 kinase and PAK1, signal transduction molecules.

Activated macrophages are the common sites for allograft inflammatory factor 1 protein, and the activated macrophages are found in inflamed tissues. The levels of allograft inflammatory factor 1 show a good correlation with various metabolic indicators like, fasting plasma glucose levels, triglycerides, and body mass index. Presence of excess adipose tissues in obese patients result in chronic inflammation and higher numbers of activated macrophages, making allograft inflammatory factor 1 a correct indicator of activated macrophages in the body. Allograft inflammatory factor 1 is also associated with diabetic nephropathy as it is a result of long term type1 and type2 diabetes. It is also responsible for decrease in insulin secretion due to its presence in activated macrophages inside the pancreatic islets.