Interleukin10 Receptor alpha (IL10 Ra), also known as IL10 R1, is a 90 110kD transmembrane glycoprotein member of the class II cytokine receptor family (1). IL10 Ra is required for mediating the effects of IL10, a critical molecule in the control of microbial infections and allergic and autoimmune inflammation (2 5). Whereas human IL10 is active on mouse cells, mouse IL10 does not act on human cells (6). IL10 Ra is the ligand specific subunit of the IL10 receptor complex. Noncovalent dimers of IL10 bind to IL10 Ra, resulting in the recruitment of IL10 RB (6 8). IL10 RB is a ubiquitously expressed transmembrane protein that does not bind IL10 by itself but is required for signal transduction and in vivo IL10 responsiveness (7, 9). IL10 RB also associates with IL20 Ra, IL22 Ra, or IL28 Ra to form the receptor complexes for IL22, IL26, IL28, and IL29 (1). Immunosuppressive signal transduction through the IL10 receptor complex can be inhibited by activation of TLR2, 4, or 9, enabling strengthened immune responses during infection (10). Some polymorphisms of human IL10 Ra may limit viral immune evasion by retaining full responsiveness to human IL10 but responding weakly to the cytomegalovirus homolog of IL10 (11). Mature human IL10 Ra consists of a 214 amino acid (aa) extracellular domain (ECD), a 21 aa transmembrane segment, and a 322 aa cytoplasmic domain (12). Within the ECD, human IL10 Ra shares 59% aa sequence identity with mouse and rat IL10 Ra. Recombinant protein corresponding to Met1-Asn235 from human IL10 Ra, N-terminal His22, expressed in Spodoptera frugiperda, Sf 21 (stably transfected). UniProt Accession: Q13651. Molecular Weight: ~24.4kD Biological Activity: Measured by its ability to inhibit IL10dependent proliferation of MC/92 mouse mast cells. ThompsonSnipes, L. et al. (1991) J. Exp. Med. 173:507. The ED50 for this effect is typically 0.05 0.25ug/ml in the presence of 2ng/ml of recombinant human IL10. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 6 months at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
