Fig. 5

Leucine-rich alpha 2 glycoprotein (LRG) contributes to the IL-6-STAT3 signaling in naïve CD4 T cells by upregulating IL-6 receptor expression. a Naïve CD4 T cells were isolated from wild-type (WT) mice and stimulated by IL-6 (100 ng/mL) or IL-6 with transforming growth factor beta (TGF-β) (2 ng/mL) in the absence or presence of recombinant LRG (1 μg/mL) for 30 minutes. Phosphorylation of Smad2 and p38 was determined by western blotting. Relative band intensities of pSmad2 and p-p38, as normalized by Smad2 and p38, respectively, are depicted at the bottom of the bands. b Naïve CD4 T cells were isolated from WT or LRG knockout (LRG KO) mice and stimulated by IL-6 (100 ng/mL) in the absence or presence of TGF-β (2 ng/mL) for 30 minutes. STAT3 phosphorylation was determined by western blotting. Relative band intensities of pSTAT3 normalized by STAT3 are depicted at the bottom of the bands. c Splenocytes were isolated from WT and LRG KO mice (n = 3 for each group) and stimulated by IL-6 (100 ng/mL) for 30 minutes. After intracellular staining, phosphorylated STAT3 in CD4 + CD62 + CD25 - cells was determined by flow cytometry. Representative data are shown in the left panel and mean fluorescence intensity of phosphorylated STAT3 (mean ± SD) is shown in the right panel: *p < 0.05. GAPDH glyceraldehyde-3-phosphate dehydrogenase