To determine whether Cl13 might be able to induce IL-10 production in polyclonal CD4 T cells in vivo, OTII cells (which express a transgenic TCR recognizing OVA peptide in the context of MHC class II) were adoptively transferred into congenic C57BL/6.SJL mice 4 days post infection with Cl13 (Fig. 5B). Here, CD4 is linked to infection.