PRELI down-regulates Th2 cell polarization. (A) Overexpression of PRELI down-regulates the number of IL-4 producing Th2 cells. CD4⁺ cells nucleofected with a control (pIRES-H2K^k) or PRELI overexpression vector were polarized into Th2 cells for 7days. Subsequently, the cells were stimulated with phorbol myristate acetate + ionomycin to induce the cytokine production or not stimulated (negative controls). Subsequently, the production of IL-4 and IFNγ was determined by intracellular cytokine staining and flow cytometric analysis. (B) Knockdown of PRELI induces the expression of a Th2 cell surface marker CRTH2. CD4⁺ cells nucleofected with scramble or PRELI-siRNAs were cultured under Th1 and Th2 polarizing conditions for 6 to 7 days. After this, CRTH2 expression was analyzed by flow cytometry. Th1 cells were used as negative controls. (A,B) Bars represent the mean values plus or minus SEM, calculated from independent experiments (overexpression, n = 3; siRNA, n = 8). Statistical significances were determined using the 2-tailed paired t test. Dot plot figures show representative data from the experiments. OE indicates overexpression.