|Cell Proliferation Induced by IL‑34 and Neutralization by Mouse IL‑34 Antibody. Recombinant Mouse IL‑34 induces proliferation in the M‑NFS‑60 mouse myelogenous leukemia lymphoblast cell line in the presence of in a dose-dependent manner (orange line), as measured by the Resazurin (Catalog # AR002). Under these conditions, proliferation elicited by IL‑34 is neutralized (green line) by increasing concentrations of Rat Anti-Mouse IL‑34 Monoclonal Antibody (Catalog # MAB5195). The ND50 is typically 0.1-0.5 ug/mL.|
Interleukin 34 (IL-34; also known as uncharacterized protein C16orf77 homolog) is a 39 kDa, secreted cytokine that belongs to no known cytokine family (1). Mouse IL-34 is synthesized as a 235 amino acid (aa) precursor with a 20 aa signal sequence and a 215 aa mature chain that contains two potential sites for N-linked glycosylation. There are three isoforms for IL-34. Isoform 1 (Q8R1R4-1) is the recombinant mouse IL-34 described in this insert. Isoform 2 (Q8R1R4-2) has an 85 aa substitution for the final 101 aa in isoform 1, and isoform 3 (Q8R1R4-3) lacks Q81 in isoform 1. Mouse IL-34 shares 71% aa sequence identity with human IL‑34. IL‑34 is expressed in various tissues, including heart, brain, lung, liver, kidney, spleen, thymus, testes, ovary, small intestine, prostate, and colon, and it is most abundant in the spleen (1). The receptor for IL-34 is colony-stimulating factor 1 receptor (CSF‑1R) (1). IL-34 stimulates monocyte viability (1). In functional studies, IL-34, like CSF-1, the other ligand for CSF-1R, stimulated phosphorylation of extracellular signal-regulated kinase-1 and -2 (ERK1/2) in human monocytes (1). In addition, IL-34 promoted the formation of the colony-forming unit-macrophage (CFU-M), a macrophage progenitor, in human bone marrow cultures (1).