PRF1 and infection: The proportion of Prf1−/−Il1rl1−/− cells within the gp33-specific subset was also markedly reduced relative to Prf1−/− cells after infection, despite similar baseline ratios of Prf1−/− to Prf1−/−Il1rl1−/− CD8+ T cells in uninfected mixed BM chimeras (Figure 6B).