Interleukin 4 induced gene 1 protein (IL4I1)

Interleukin 4 induced gene 1 protein (IL4I1) is a secreted L-amino acid oxidase primarily expressed by antigen-presenting cells. It catalyzes the oxidative deamination of L-amino acids, producing hydrogen peroxide, ammonia, and keto acids. IL4I1 acts as a metabolic immune checkpoint protein, inhibiting effector T cell proliferation, promoting regulatory T cell differentiation, and enhancing M2 macrophage polarization. It plays roles in cancer, cardiovascular disease, and autoimmunity.

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Inhibits effector T cell proliferation, promotes regulatory T cell differentiation, enhances M2 macrophage polarization, suppresses CD8+ T-cell cytotoxicity, downregulates CD3 chain expression on the T-cell receptor complex