CD4 and neoplasm: Cell surface binding of NDV can stimulate the tumor-specific cytotoxic CD8+ T-cell (CTL) response and increase CD4+ T-helper cells’ activity even in the absence of an antiviral T-cell response and cell infection.105 The activation and infiltration of tumor sites with CTLs is the result of complex effects of virus triggered immune system, including local and systemic release of IFNs and other cytokines.