Infection with recombinant VSV-ova induces anti-ova peripheral and mucosal primary CTL. VSV-ova induces primary anti-ova CTL in LN T cells and IEL. LN cells or IEL from CTLA4-Ig-mut-treated mice (■, LN; •, IEL) or CTLA4-Ig treated mice (□, LN; ○, IEL) were tested for lytic activity against ova-peptide-coated EL4 cells. LN cells and IEL from CTLA4-Ig-mut-treated mice reacted with EL4 cells in the absence of peptide (▴, IEL; ▾, LN). Effector-to-target ratios were adjusted to actual donor cell percentages found in CTLA4-Ig-mut-treated mice. This experiment has been performed three times with similar results. SE bars are shown.