Perforin and granzyme B expression in oral and cutaneous lichen planus - a comparative study

Abstract

Although cutaneous and oral lichen planus (LP) share similar histopathological features, oral LP often follows a recalcitrant course while LP skin lesions tend to be self-limiting. Apoptosis, mediated by cytotoxic T-cells in LP, may be triggered by the release of molecules such as perforin and granzyme B. As variation in clinical behavior can reflect differences in LP immune expression, we studied the role of those cytotoxic molecules in oral and cutaneous LP. We analyzed 16 cases of cutaneous LP and 29 of oral LP. The sections were studied on hematoxylin and eosin, CD4, CD8, perforin and granzyme B staining. The mean number of immunostained cells expressing each cytotoxic molecule was significantly higher in oral LP than in cutaneous LP. A higher number of single necrotic keratinocytes (apoptotic bodies) was found in oral LP lesions when compared to cutaneous LP. Only in oral LP lesions, a higher number of CD4-positive cells was found in active lesions when compared to regressive lesions. Our results confirm increased expression of granzyme B and perforin in oral LP lesions as compared to cutaneous LP. The increased expression suggests a relationship with the clinical behavior of the disease.