Mucosal protection vs. circumcision
Mucous membranes are what surround bodily orifices to bar infections from entering. They contain anti-viral cells and enzymes.
Langerhans cells in the vagina, vulva, and inner foreskin are the body’s first line of defense against sexually transmitted infections, but in males, their function is sometimes misunderstood. Shortly after the discovery of the HIV virus in the 1980s, American circumcision advocate Aaron J. Fink nominated them as “target cells” for HIV infection, snowballing a wealth of circumcision-promoting literature that led to WHO/UNAIDS’ acceptance of the Langerhans cell theory and the clinical trials that inform VMMC.
Wait-and-wash men are at lower HIV risk than circumcised men (IRR 0.13, 95% CI) (Makumbi et al., 2007).
In short, Langerhans cells in the foreskin provide the penis’ only known HIV protection.
But don’t Langerhans cells recruit and bond to T-cells which are susceptible to HIV infection? This study is sometimes used to promote male circumcision, with a belief that Langerhans cells pass on the virus to T-cells. However there is no evidence for this belief, and contrary evidence that Langerhans cells trap HIV-1 into Birbeck granules where the virus is degraded. Bonding to T-cells may be beneficial to leech and remove HIV, reducing the risk of infection. Not only do Langerhans cells destroy the virus — they may actively protect T-cells from infection.
What about keratinisation? See our analysis here [WARNING: graphic images].
Just as the tonsils were found to be a functional part of the immune system (stemming the former medical trend of routine tonsillectomies), there is growing awareness of the foreskin’s role in sexual immunology — including some degree of HIV protection — that is raising new questions as to whether the routine removal of this mucous membrane is beneficial or medically harmful.
Related: See our analysis of VMMC’s clinical trials.