Host defense mechanisms in polyaromatic hydrocarbon carcinogenesis

Polyaromatic hydrocarbons (PAHs) are chemicals that are widely employed to examine the complex mechanisms by which chemicals cause cancer. While it is clear that the tumors that carcinogenic PAHs produce elicit an immune resp onse, the interplay between host immune defense mechanisms and earlier stag es in the cutaneous carcinogenesis pathway has received little attention. S tudies from our laboratories have shown that topical application of several different PAHs to mice results in the development of an antigen-specific c ell-mediated immune response to them. The response is genetically determine d and is mediated by CD8+ T cells. Development of a cell-mediated immune re sponse is associated with resistance to dimethyl benz(a)anthracene tumorige nesis. These findings are consistent with the hypothesis that host defense mechanisms against PAHs help to protect individuals from the carcinogenic a ctions of these agents. This may form the basis for novel immunopreventive strategies for individuals at high risk for development of tumors produced by PAHs. Copyright (C) 2001 S. Karger AG, Basel.