PRT-treated platelets do not induce cytokine production by splenic T cells and alter the cytokine response to subsequent untreated platelets. Splenocytes from mice described in Figure 3 were stimulated for 3 hours and then stained for intracellular cytokine expression. (A) Cells were gated on CD3⁺/non-T-cell marker⁻, CD4⁺, or CD8⁺ T cells and IFN-γ⁺. (B) CD4⁺ T cells were gated on IL-10⁺, IL-4⁺, IL-13⁺, and IL-5⁺. (C) Heat map shows fold changes of each group compared with the nontransfused group for frequencies of cytokines out of total CD4⁺ T cells (top) or CD8⁺ T cells (bottom). CD8⁺ T cells did not meet threshold of 25 positive events for cytokines IL-10, IL-4, IL-5, and IL-13 and were therefore excluded (X). Data from 2 independent experiments are shown (n = 5 per group). *P < .05, **P < .01, ***P < .001, ****P < .0001.