Class II cytokine receptor family

The class II cytokine receptor family includes receptors for interferon a/P (lEN a/P) and y (lENy) and IL-10. lEN-y immunoreactivity has been found in neurons in the hypothalamus, cerebral cortex, mammilary nuclei, and dorsal tegmentum. Astrocytes and microglia in vitro can be stimulated to express class II histocompatibiHty complex (MHC-II) antigens by lEN-y, which may be involved in the presentation of antigen to T-ceUs by astrocytes. Thus lEN-y may be critical in CNS-immune function and dysfunction especially in regard to neuronal and gHal apoptotic processes. 

Studies have actually revealed two type I interferon receptor polypeptides. Sequence data from cloning studies place both in the class II cytokine receptor family. Both are transmembrane N-linked glycoproteins. Studies using isolated forms of each show that one polypeptide (called the a/p receptor) is capable of binding all type I interferons. The other one (the ap receptor) is specific for IFN-a-B (a specific member of the IFN-a family). Both receptors are present on most cell types. 

IL-22. IL-10-related T cell-derived inducible factor (IL-TIF provisionally designated IL-22) is a cytokine distantly related to IL-10 and is produced by activated T cells (D16). IL-22 receptor, a new member of the interferon receptor family, and CRF2-4, a member of the class II cytokine receptor family, join together to enable IL-22 signaling. Cell lines that respond to IL-22 by activation of STATs 1,3, and 5, but unresponsive to IL-10, have been identified (XI). In contrast to IL-10, IL-22 does not inhibit the LPS-induced production of proinflammatory cytokines by monocytes, but it has a modest inhibitory effect on IL-4 production from Th2 cells (XI). 

IL-IOR is a single-chain receptor. IL-IOR belongs to the class II cytokine receptor family that also includes the IFN receptors (IFNy and IFNap receptors). The extracellular region consists of two homologous fibronectin type III domains that are without the WSXWS motif characteristic of class I cytokine receptors. It is expressed on B cells, thymocytes, and other cellular lines such as mast cells and macrophages. Human IL-IOR mRNA is restricted mostly to hematopoietic cells and cell lines. ... 

The first specifically binds IFNaB (IFNaS, a variety of IFNa) and is known as the IFNaB receptor. The second bmds both IFNa and IFNp and is called the IFNa/j3 receptor. The IFNapR is a member of the class II cytokine receptor family, which also includes the IFNyR, IL-IOR, and tissue factor. The IFNa/ R is also a class II cytokine receptor and contains at least two components that interact with type I IFNs, It is not known if these two receptors are expressed independently on the cell surface or are associated with each other in an IFN receptor complex. The receptors are present on most types of cells. A soluble form of the IFNa/pR has been identified in human serum and urine. 

NERON D (2003), Comparative genomic analysis reveals independent expansion of a lineage-specific gene family in vertebrates the class II cytokine receptors and their ligands in mammals and fish , BMC Genomics, 4, 29. 

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