We observed that the PD-L1 BiTE could mediate significant activation of both CD4+ and CD8+ T cell subsets, in line with the concept that most T cells (even those expressing PD-L1, data not shown) can be repurposed for BiTE-mediated cytotoxicity.7 The immunosuppressive effects of ascites fluids on lymphocytes are well established.47 Nevertheless, BiTE-mediated activation of endogenous T cells was maintained in the presence of immunosuppressive malignant ascites fluids (figure 4A, B), suggesting that BiTE-mediated activation may overcome local immunosuppressive effects. The gene discussed is CD4; the disease is cancer.