Plots show 4-hour 51Cr-release cytotoxicity assays against YAC-1, P52, and NCTC929 (L-929) continuous cell lines and against cultured Th0, Th1, and Th2 differentiated effector T cell targets. Solid lines represent lysis by day 3 LCMV-induced C57BL/6 mouse spleen leukocytes, and dashed lines represent lysis by spleen leukocytes from uninfected mice.