CD8A and neoplasm: To further validate this discovery, CD8 + T cells are further classified into three groups: (1) Ly108+ progenitor T cells (Tpro), with high capacity to produce IFN-γ and TNF-α, (2) CX 3 CR1− Ly108− exhausted T cells (Texh) with the lowest potential to produce inflammatory cytokines, represented as truly exhausted phenotype; (3) CX 3 CR1+ cytolytic T cells (Teff) with capacity to expression Granzyme B and cytolytic function, during persistent infection or tumor progression [16].