Abstract: Although persistent infection with an high-risk human papilloma virus（HPV）is thought to be necessary for most cervical tumorigenesis， most infections have been shown to regress spontaneously under an effective immune response， often within a few months. So understanding the factors that affect the balance between viral persistence and viral clearance and the role of the immune system in these processes is important. As HPV infection happens in the local of female lower genital tract， the local immune milieu in the lesion plays an important role. Recent researches show that nitric oxide（NO）is a key component in inflammation-accelerated tumorigenesis. HPV infection and other risk factors for cervical cancer（e.g. smoking， multiparity， inflammation）can lead to high local NO concentration in the cervix， which may result in malignant progression.

Key words: Nitric oxide, Papillomaviridae, Immunoassay, Uterine cervical neoplasms, Local immune milieu