In order to assess the impact of tumor-derived immunosuppressive factors on the T cell-stimulatory capacity of CD40-activated B cells we compared the ability of CD40-activated B cells which were treated with IL-10, TGF-β, or VEGF to induce the proliferation of CFSE-labeled CD4+ or CD8+ T lymphocytes from healthy HLA-mismatched donors. The gene discussed is CD40; the disease is neoplasm.