CXCR5 and infection: Thus, to specifically investigate a role for CXCR5+CD8+ T cells in mediating IgG2c class switching in response to IAV, we transferred WT or Cxcr5-/- OT-I cells into B6.Ifng-/- mice, infected the recipients with x31-OVA and harvested the mLNs on day 6 post-infection for flow cytometric analyses (Figure 5A).