Xeroderma pigmentosum skin: an immune privilege site for tumor development.

A unique feature of the skin immune system is its proximity to cells continuously exposed to sun rays, as it is located in the interface between the body and the environment. In this study, we aimed to determine the impact of DNA damaged keratinocytes on the expression of apoptotic-related molecules, in T-cells of the inflammatory component of the tumor environment. Immunohistochemistry was performed on tissue sections derived from skin biopsies of basal cell carcinomas (BCCs) of xeroderma pigmentosum (XP) patients, non-XP patients and nevoid basal cell carcinoma syndrome (NBCCS) patients, using antibodies against B-cell lymphoma/leukemia-2 (Bcl-2), Bcl-2 associated X protein (Bax), CD95, CD3, CD8 and CD56. Our results showed significantly lower levels of expression of the antiapoptotic Bcl-2 molecule, in XP, in comparison with non-XP and NBCCS T-lymphocytes, leading to the highest Bax/Bcl-2 ratio for XP T-cells. For the CD95 receptor expression levels, there were significant differences among T-cells of the three patient subgroups as well. The higher propensity of XP T-cells to undergo apoptosis may have evolved in individual XP patients, apparently during the course of their disease, to maintain a special skin as an immune privilege site for tumors' development.