CD4 and cancer: However, the neoplastic follicles also contain non-neoplastic cells that constitute the TME such as CD4+ follicular helper T-cells (Tfh), CD4+ follicular regulatory T-cells (Treg), CD8+ cytotoxic T-cells, follicular dendritic cells (FDCs), cancer-associated fibroblasts (CAFs), and tumor-associated macrophages (TAMs).