Depletion of activated Vβ8+ T cells disrupts bispecific antibody directed antitumor immunity1

Introduction Activation of Vβ8+ T cells with superantigen staphylococcal enterotoxin B (SEB) and use of an antitumor, anti-CD3 bispecific antibody (BsAb) leads to tumor protective immunity. We hypothesize that Vβ8+ T-cell activation in combination with BsAb is crucial for tumor protective immunity in this model. Methods Adolescent C3H/HeN mice were intravenously injected with syngeneic CL62 melanoma to establish pulmonary metastasis. Three days after establishing pulmonary metastasis, predominantly Vβ8+ T cells are activated with 50 μg of intraperitoneal superantigen SEB. T cells were depleted at different time points in relation to SEB administration to assess the effect on protective immunity against a second tumor challenge. Results Protective immunity is significantly ( P P P P Conclusions Depletion of Vβ8+ T cells 6 h after activation disrupts the development of protective immunity.