Interleukin 13 (IL-13) is a protein that in humans is encoded by the IL13 gene. IL-13 was first cloned in 1993 and is located on chromosome 5q31 with a length of 1.4kb. It has a mass of 13 kDa and folds into 4 alpha helical bundles. The secondary structural features of IL-13 are similar to that of Interleukin 4 (IL-4); however it only has 25% sequence homology to IL-4 and is capable of IL-4 independent signaling. IL-13 is a cytokine secreted by T helper type 2 (Th2) cells, CD4 cells, Natural killer T cell, Mast cell, Basophil cells, Eosinophil cells and Nuocyte cells. Interleukin-13 is a central regulator in IgE synthesis, goblet cell hyperplasia, mucus hypersecretion, airway hyperresponsiveness, fibrosis and chitinase up-regulation. It is a mediator of allergic inflammation and different diseases including asthma.
mRNA expression analysis
Strain specific analysis of IL13 gene expression in WT and B-hIL13 mice by RT-PCR. Mouse Il13 mRNA was detectable in thymocytes of wild-type (+/+) but not in homozygous B-hIL13 mice (H/H) mice. Human IL13 mRNA was detectable only in homozygous B-hIL13 mice but not in wild-type mice.
Protein expression analysis
Strain specific IL13 expression analysis in homozygous B-hIL13 mice by ELISA. CD4+ T cells were collected from WT and homozygous B-hIL13 (H/H) mice, and then induction of CD4 + T-cells differentiation into Th2 cells, supernatant from Th2 cells culture was analyzed by ELISA with species-specific IL13 ELISA kit. Mouse Il13 was detectable in WT mice. Human IL13 was exclusively detectable in homozygous B-hIL13 mice but not WT mice.