TNF and infection: Indeed, the profiling data from the study by He and colleagues also demonstrate that the CXCR5+CD8+ T cells isolated from later time points express more IFNγ and TNFα compared to their CXCR5- counterparts, while they observed similar frequencies of cytokine-producing cells at day 8 post-infection, indicating both CXCR5+ and CXCR5- CD8+ T cells late during chronic infection are phenotypically distinct from early cells and therefore likely differ functionally.