Although the correlation with Perf/GzmB expression may be prone to underestimation because of the prior release of cytotoxic molecules in vivo during ongoing infection, ∼5% of Perf/GzmB+ pMHCII tetramer+ CD4+ T cells lacked expression of Eomes, Hobit, and CX3CR1. This evidence concerns the gene CX3CR1 and infection.