GZMB and infection: Perforin and GrB analysis was performed at wks-2 (pre-infection), 2 (pre-IL-21 administration), 4 and 6 (during IL-21 treatment), 10 and 23 p.i. in PBMC; at wks-2, 2, 4, 6 and 23 in RB and at wks-2, 2, 6 and 23 in LN.