[87coupe]

http://www.infoforhealth.org/pearls/2002/06-10.shtml

The interior side of the foreskin has a mucosal surface which is more susceptible to trauma than the tougher skin of the penile shaft or the glans. Moreover, the foreskin contains high levels of HIV target cells (such as Langerhan's cells). Indeed in a recent in vitro study of 14 foreskins, investigators from Chicago found that foreskin mucosal tissue had a 7-fold greater susceptibility to HIV-1 than cells in cervical tissue under the same conditions. Lastly, the presence of a foreskin appears to increase risk of ulcerative STDs such as chancroid and herpes, which are strong co-factors for HIV infection.

Thus there appears to be good biologic plausibility to the epidemiologic finding that male circumcision reduces risk of HIV infection.