Similarly, after gating on CD19+GrB+ cells, the number of GrB-expressing B cells also expressing CD73 was found to increase at D-6 post-secondary infection with 16,314 ± 4,067 expressing the CD73 marker at Pre-SI and 44,828 ± 8,719 at D-6, and 12,774 ± 2,162 vs. 135,144 ± 38,099 for CD19+GrB+CD73- B cells at Pre-SI and D-6 respectively (S3B Fig). Here, CD19 is linked to infection.