Interleukin 9, Recombinant, Rat (IL-9)

Rat interleukin-9 (IL-9, also T-cell growth factor P40 and MEA) is a 20-30 kD secreted glycoprotein that belongs to the IL-7/IL-9 family of hematopoietic cytokines. It is best considered an atypical Th2-type cytokine. 1-4 Rat IL-9 was initially isolated from the 4437A rat thymoma cell line. 5 The IL-9 precursor is 144 amino acids (aa) in length and contains an 18 aa signal sequence plus a 126 aa mature segment. 5 An extended, 219 aa alternate precursor form is reported in GenBank (Accession # XP_001068265). It shows a 113 aa substitution for the first 38 aa of the standard form. Its significance is unknown. Mature rat IL-9 is 75%, 74% and 58% aa identical to cotton rat, mouse and human IL-9, respectively. 6-9 There is variability in cross-species reactivity. Canine and mouse IL-9 are purportedly active on human cells, 9-11 while human IL-9 is inactive on mouse cells. 9 Cells reported to express IL-9 include activated CD4+ T cells and eosinophils. 12, 13 The receptor for rat IL-9 is composed of the 62 kD rat IL-9Ra chain and the 64 kD rat common cytokine receptor g-chain. 5, 14, 15 IL-9 is suggested to play a significant, but likely supporting role in allergy and asthma. Its synthesis is induced upon exposure to allergen. 10, 13 Following release, it is known to upregulate IgE production by IL-4-stimulated B cells. 16 It also stimulates mucin secretion and IL-13 production through a direct action on respiratory epithelium. 10, 17 In the bone marrow, it promotes eosinophilia, likely through IL-5 induction. 18, 19 And once produced, eosinophils are chemoattracted to the bronchi through the IL9-induced secretion of eotaxin-1 by airway smooth muscle cells. Molecular Mass: The mature recombinant rat IL-9, generated by proteolytic removal of the signal peptide region, is a monomer protein. Based on N-terminal amino acid sequencing, the recombinant rat IL-9 starts at Gln 19. It has a calculated molecular mass of 14.1 kD. As a result of glycosylation, the recombinant monomer is heterogeneous and it migrates as an approximately 30-35 kD protein in SDS-PAGE under reducing conditions. Endotoxin Level:< 1.0 EU per 1ug of the protein as determined by the LAL method. Biological Activity: Measured in a cell proliferation assay using a factor-dependent mouse cell line, TS1., , Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute by adding PBS containing 0.1% HSA or BSA. Reconstituted product is stable for 3 months at -20ºC. 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.