Interleukin-19

Interleukins (from Latin/Greek inter = between; leukos = white; kinein = to move) are a group of endogenous, short-chain regulatory proteins (cytokines) of the immune system (IL1-IL38). Interleukins are mediators for induction, course and control of T-cell-mediated cytotoxic immune reactions as well as B-cell activation (antibody production). They are mainly formed and secreted by stimulated leukocytes, monocytes and macrophages. So far, about 38 different interleukins have been clearly identified. Each cytokine of the interleukin group is nomenclatically assigned a number for its classification (IL-1 to IL-38).

Some structurally related substances have been grouped into families. Their members often have a similar function or participate in the fine regulation of immune reactions, for example by regulating the synthesis of related interleukins. IL19 belongs to the Interleukin-10 family with the following members: Interleukin-10, Interleukin-20, Interleukin-22, Interleukin-24, Interleukin-26. The Interleukin-10 is homologous to Interleukin-IL19 (21% amino acid identity) and Interleukin-20

The Interleukin-10 cytokine family is organized in a tightly coordinated cluster (Interleukin-10 cluster) on chromosome 1q321. The IL-19 gene is expressed by resting monocytes and B cells.

The Interleukin-10 family comprises multifunctional cytokines with anti-inflammatory properties that consist in the "regulation" of antigen presentation and macrophage activation. Interleukin-10 and Interleukin-19 are immunoregulatory cytokines, while Interleukin-20 is pro-inflammatory.

The cytokine is preferentially formed and secreted by monocytes. Interleukin-19 binds to the Interleukin-20 receptor complex and leads to the activation of the "signal transducer and activator of transcription 3" = STAT3 signaling pathway.

The granulocyte-macrophage colony stimulating factor (GM-CSF) and lipopolysaccharides are able to induce IL19 expression.

Interleukin-19 also plays a role in B-cell activation and antibody production. Interleukin-10 and interleukin-19 are immunoregulatory cytokines, while interleukin-20 is pro-inflammatory.

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