CD4 and neoplasm: TILs can be further categorized into various cell types, including CD8+ cytotoxic T lymphocytes, CD8+ tissue-resident memory T (TRM) cells, natural killer (NK) cells, CD4+ T helper 1/2/17 (Th1, Th2, and Th17) cells, CD4+ regulatory T cells (Tregs), CD4+ follicular helper (Tfh) T cells, and tumor-infiltrating B cells (Table 2) [42].