CD4 and infection: We examined expression of PD-1 on CD4 and CD8 T cells following single-hit and two-hitCandida infection.Mice were injected with Candidaand spleens were harvested on days 3, 5 and 7 following infection.Splenocyte suspensions were prepared and stained for CD4 or CD8 and PD-1 as described previously [13].There was a significant increase in PD-1 expression on CD4 T cells at all three time points compared to Day 0 (Figure 3A).There wasan increase in PD-1 expression in CD8 T cells at days 3 and 5 following Candida infection as well (Figure 3B).