Figure 3. α-lactalbumin specific T cells induce tumor inflammation and cytotoxicity.
(a) Thirty-two days after BALB/c mice were vaccinated with α-lactalbumin and inoculated with 4T1 cells, tumors were extensively infiltrated with CD3+ T cells. (b) T cell infiltrates were never observed in control inoculated mice immunized with CFA alone. (c) Flow cytometry analysis of TILs showed a predominance of CD4+ (64.3%) over CD8+ (14.4%) T cells. (d) TILs showed a type-1 proinflammatory phenotype involving high production of IFN-γ in response to 50 μg/ml α-lactalbumin. (e) ELISPOT analysis of TILs showed that CD4+ rather than CD8+ T cells produced IFN-γ in response to 50 μg/ml α-lactalbumin since its secretion by cultured T cells was inhibited by treatment with class II but not class I antibodies. (f) CD8+ T cells mediated 4T1 specific cytotoxicity since death of cultured 4T1 tumor cells was inhibited by treatment of cultured α-lactalbumin primed LNC with antibodies specific for mouse CD8 but not CD4. All data shown are representative of three experiments providing similar results. All error bars show ±SE.