CB6F1 skin graft rejection is associated with Th2-cell priming and strong eosinophil infiltrates in the absence of CD8 T cells. WT or CD8-deficient B6 mice received a skin graft from semi-allogeneic CB6F1 mice. (A) At the time of graft rejection (day 10-11), draining lymph nodes were harvested. Purified CD4 T cells were cultured (3 × 10⁵ cells/well) in the presence of allogeneic (BALB/c) irradiated splenocytes for 72 hours. CD4 T-cell proliferation was evaluated by ³H-TdR incorporation. IFN-γ and IL-4 production were measured by ELISA in 72-hour culture supernatants. Results are expressed as mean plus or minus SEM of 6 mice per group and are from 1 representative experiment of 3 performed. (B,C) WT or CD8-deficient B6 mice received a skin graft from semi-allogeneic CB6F1 mice and one group of CD8^–/– B6 mice was intravenously injected with WT CD8⁺ T cells 1 day prior to skin transplantation. Skin grafts and graft-draining lymph nodes were harvested the day the grafts were fully rejected. (B) Purified CD4⁺ T cells were cultured (2 × 10⁵ cells/well) in the presence of irradiated BALB/c splenocytes (3 × 10⁵ cells/well). IFN-γ and IL-4 production in 72-hour culture supernatants were measured by ELISA. Results are expressed as mean plus or minus SEM of 3 to 4 mice per group and are from 1 representative experiment of 3 performed. (C) Skin graft histology was performed and the percentage of eosinophils among total cell infiltrates was evaluated as described in “Materials and methods” (3-4 mice per group). Statistical significance of difference between groups was evaluated by the Mann-Whitney U test (*P < .05; NS, not significant).