Effects of PD-1 and BTLA signaling on IL-2 production in WT, SHP1 KO, SHP2 KO, and SHP1/2 DKO Jurkat cells. (A) Raw IL-2 levels in the medium of the indicated Raji-Jurkat co-cultures. Data are means ± SD from six to nine independent experiments. These are also the raw data for Fig. 6, F–H. (B) Raw IL-2 levels in the medium of the indicated Raji-Jurkat co-cultures, using Jurkat clones based upon the Jurkat E6.1 recently obtained from ATCC. Data are means ± SD from four independent experiments. (C) Scatter plots showing relative IL-2 levels of the indicated Raji-Jurkat co-cultures. Data are the same as B, except that in each replicate IL-2 levels of Jurkat (PD-1^WT–mGFP⁺) or Jurkat (BTLA^WT-mGFP⁺) were normalized to that of Jurkat (PD-1^FF–mGFP⁺) or to that of Jurkat (BTLA^FFFF-mGFP⁺) under the same SHP background, respectively (see Materials and methods). **, P < 0.01; ****, P < 0.0001; ns, not significant; Student’s t test (n = 4).