Leukocyte cell–derived chemotaxin 2 (LECT2) is a secretory protein originally identified in the process of screening for a novel neutrophil chemotactic protein. Although the original characterization of LECT2 proved to be of bovine origin from the fetal calf serum used in media, these studies led to the cloning and structural characterization of the human analogue. The human LECT2 gene consists of four exons and three introns. It has been mapped to chromosome 5q31.1-q32, a cluster harboring several genes encoding immunoregulatory cytokines. The gene codes for 151 amino acids (MW 16.38 kDa) including an 18 amino acid signal peptide. The secreted protein has 133 residues. LECT2 is expressed preferentially by human adult and fetal liver cells and is secreted into the bloodstream, which negatively regulates the homeostasis of natural killer T cells in the liver. It is a multi-functional protein that is involved in chemotaxis, cell proliferation, inflammation, immunomodulation and carcinogenesis. Along with neutrophil chemotactic properties, it is also believed that LECT2 plays a role in tissue growth and repair following damage. LECT2 is involved in many pathologic conditions. It has been identified as one of the proteins associated with human systemic amyloidosis. Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is one of the amyloidosis forms, which most commonly affects the kidney and liver primarily in people of Hispanic ethnicity. Studies report that LECT2 may function in immunological events such as hepatitis and arthritis, hepatocarcinogenesis, and the negative regulation of the Wnt receptor signalling pathway in the small intestine. LECT2 significantly induces adhesion molecules and pro-inflammatory cytokines in Human umbilical vein endothelial cells, suggesting that such liver-derived hepatokine might directly mediate atherosclerotic inflammatory reactions in human endothelial cells. Recent studies indicate the possible involvement of LECT2 in metabolic diseases and suggest that LECT2 could be a novel obesity-related protein. Serum LECT2 levels were found to be increased by obesity and fatty liver, and LECT2 was shown to be a link between obesity and skeletal muscle insulin resistance. Circulating LECT2 positively correlates with the severity of both obesity and insulin resistance in humans. LECT2 could potentially be a key player in the development of hepatocellular carcinoma (HCC). It was shown that re-expression of LECT2 significantly reduced the migration and invasion of human HCC cells in vitro and significantly reduced their growth in vivo.