Cytokine production patterns in cervical intraepithelial neoplasia: association with human papillomavirus infection

Abstract

Background: Genital infection with certain strains of human papillomavirus (HPV) is associated with a high risk of malignant transformation, and HPV-associated cervical intraepithelial neoplasia (CIN) can become invasive cancer. Host factors are critical in regulating tumor growth, and cytokines that modulate immunologic control may be of particular importance. The type 1 cytokines interleukin 2 (IL-2) and interferon gamma (IFN gamma) are immunostimulatory and are thus capable of limiting tumor growth. The type 2 cytokines interleukin 4 (IL-4) and interleukin 10 (IL-10) are immunoinhibitory and are thus capable of stimulating tumor growth.

Purpose: We analyzed the production of cytokines by peripheral blood mononuclear cells (PBMCs) in women with CIN associated with localized or extensively spread HPV infection.

Methods: Thirty women diagnosed with CIN and 10 age- and sex-matched healthy control subjects were enrolled in the study conducted at Istituto Nazionale Tumori, Milan, Italy. The following parameters were analyzed: 1) HPV infection of the cervix and other sites of the lower genital tract by colposcopic, cytologic, and histologic examinations; 2) HPV typing; 3) in vitro production of IL-2 by PBMCs in response to stimulation with soluble antigen (influenza [FLU] antigen) or to cell-associated human leukocyte antigen (HLA) alloantigen; and 4) in vitro production of the type 1 cytokines IL-2 and IFN gamma and of the type 2 cytokines IL-4 and IL-10 by PBMCs in response to mitogen stimulation. Statistical significance was determined by nonparametric tests (two-sided).

Results: High-grade CIN associated with HPV infection was detected in all case patients, and HPV type 16 or 18 infection was detected in cervical tissue of 21 (70%) of 30 case patients. HPV infection that had spread to other sites of the lower genital tract, thus resulting in more extensive disease, was detected in 16 (53%) of the 30 individuals with CIN, whereas HPV infection was limited to the portio in 14 (47%). IL-2 production by PBMCs in response to stimulation with soluble antigen or HLA alloantigen was reduced in the group with extensive disease compared with that in the group with localized disease or with that in healthy control subjects. In contrast, IL-4 and IL-10 production in response to mitogen stimulation was elevated in the group with extensive disease compared with that in the group with localized disease or with that in healthy control subjects. The highest production of IL-4 and IL-10 was detected in patients with HPV infection that had extended beyond the genital tract.

Conclusions: CIN is characterized by different immunologic profiles, in which HPV infection is or is not confined to the portio. Production of cytokines that mainly enhance potentially protective cell-mediated immunity is defective in the women in whom extended HPV infection was observed. A pronounced shift from type 1 to type 2 cytokine production is associated with more extensive HPV infection.

Implications: These data reinforce the need for detailed analyses of immune dysregulation in CIN patients. They also suggest the potential usefulness of the cytokine assays for determining prognosis or deciding whether cytokine-based therapy is indicated.