Figure 2.

CD137 transcription and protein expression are costimulated by CD137 on mouse CD8 T cells. (A) Mouse CD8 splenocytes were cultured with plate-bound anti-CD3ε mAb in conjunction or not with anti-CD28 or anti-CD137 mAbs and the levels of soluble and transmembrane-encoding mRNAs were measured by quantitative RT-PCR. (B) sCD137 concentrations in the tissue culture supernatants and (C) surface expression of CD137 on the corresponding T cells. (D) As a control of the cell costimulation, the immunostaining levels of CD25, CD69 as well as the % of positive cells for Ki67 and PD1 assessed by immunostaining and flow cytometry are provided. Bars indicate mean±SEM. Statistical significance was assessed by Student’s standard and ratio paired t-test in parts A, B, C, and D, as appropriate. *p<0.05. These experiments were repeated three times. mAb, monoclonal antibodiy; MFI, mean fluorescence intensity; ns, not significant.