CD4 and cervical carcinoma: In pancreatic breast and cervical cancer, the engagement of PD1 with PD-L1, expressed on Bregs cells surface, induces CD4+ and CD8+ T cell suppression and exhaustion, IL-10-secreting type-1 regulatory CD4+T cells (Tr1) expansion, and reduced Th1/Th17 responses [94,95,96].