| 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-9Ralpha chain and the 64 kD rat common cytokine receptor gamma-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. 20 Source: A DNA sequence encoding rat IL-9 (Met 1-Ala 144) (Accession XP_341488) was expressed in a mouse myeloma cell line, NS0. 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 1 µg of the protein as determined by the LAL method. Activity: The biological activity of recombinant rIL-9 was measured in a cell proliferation assay using a factor-dependent mouse cell line, TS1 (Uyttenhove, C. et. al., 1988, Proc. Natl. Acad. Sci. 85:6934-6938). The ED 50 for this effect is typically 3-15 ng/mL. Reconstitution: It is recommended that sterile PBS be added to the vial to prepare a working stock solution of no less than 100ug/ml. The carrier-free protein should be used immediately upon reconstitution to avoid losses in activity due to non-specific binding to the inside surface of the vial. For long term storage as a dilute solution, a carrier protein (e.g. 0.1% HSA or BSA) should be added to the vial. Storage and Stability: Lyophilized samples are stable for up to twelve months at -20C. Upon reconstitution, this protein, in the presence of a carrier protein, can be stored under sterile conditions at 2-8 C for one month or at -20C in a manual defrost freezer for three months without detectable loss of activity. Avoid repeated freeze-thaw cycles. |
