As a negative control (see Supplementary Figure S2), LDH release and cytokines secretion, following treatment with the immunomodulatory mAbs, were also measured when unfractionated hPBMCs (Supplementary Figure S2A) or the two subpopulations (Supplementary Figure S2B,C) were co-cultured with the breast cancer MCF-7 cell line, which is PD-L1-negative and expresses low levels of CTLA-4 [42]. Here, CTLA4 is linked to breast cancer.