Figure 5.

CD4+ T cell cytotoxicity against MHC II+ target cells. Target cells for the CD4+ T cell cytotoxicity assay were obtained from lymph nodes and spleens of naïve mice, loaded with epitope peptides and injected into FV-infected recipient mice. The target cell population was depleted for T cells to increase the frequency of possible MHC II+ targets. (A) Distribution of different target cell populations in the lymph nodes of naïve recipient mice. (B) Frequencies of killed cells indicated that CD19+ B cells were the main targets of cytotoxic CD4+ T cells. The data were pooled from two independent experiments with similar results.