Initial infections of some types of HPV can be controlled by innate immunity, while clinically evident lesions require a local immune response involving CD8+ cytotoxic T lymphocytes and T helper 1 CD4+, which produce interleukin 2 (IL-2) and interferon-gamma (IFN-γ) and recognize the viral proteins E6, E7, and E2. Here, IL2 is linked to infection.