BTLA and hematologic disorder: Additional evidence for BTLA‐mediated suppression of antitumor T cells comes from a study reporting that BTLA blockade enhances the proliferation, effector cytokine production, and degranulating activity of minor histocompatibility Ag‐specific CD8+ T cells isolated from PBMC of patients with hematological malignancies that were treated by allogeneic stem cell transplantation.213