Mucosal immune responses to hepatitis C virus

Sexual transmission has been suggested as a route of hepatitis C virus (HCV) transmission, and this is supported by some epidemiologic data; however, the data are not conclusive. Identification of a marker for sexual exposure to HCV would help identify conditions and behaviors which lead to sexual transmission. These studies evaluate whether the production of IgA specific for HCV is associated with sexual exposure to HCV and/or risky sexual behaviors. Studies were carried out evaluating cervical mucosal IgA production and serum IgA production. Uninfected women sexually exposed to HCV+ men were not found to make a cervical or serum IgA response to HCV antigen. In a cross-sectional study, HCV-infected women sexually exposed to HCV-infected men were found to make both cervical and serum anti-HCV IgA, and the production of cervical anti-HCV IgA was related to sexual behavior variables. In a longitudinal study, the concentration of serum IgA was found to increase as the frequency of report of HCV+ sexual partner increased in women reporting a past or current sexually transmitted disease diagnosis. These results show that cervical mucosal as well as serum anti-HCV IgA is produced in HCV+ women, and suggest that the production of this antibody is associated with sexual behaviors. This study supports the possibility of sexual exposure to or transmission of the hepatitis C virus.