Interleukin 34 (IL-34) is a member of the short-chain helical hematopoietic cytokine family and exists in two isoforms that differ by a single glutamine. IL-34 interacts with M-CSF to trigger tyrosine phosphorylation of the receptor and ERK1/2 pathways. In combination with RANKL, IL-34 induces osteoclast differentiation. IL-34 expression is decreased in Alzheimer's disease and atopic dermatitis, while high levels of IL-34 are found in many types of cancer correlated with poor prognosis, chronic heart failure or coronary artery disease, inflammatory bowel disease, influenza A infection, during acute liver transplant rejection or in non-alcoholic fatty liver disease, and with rheumatoid arthritis.
