P-19   APOPTOSIS IN PATCHY ALOPECIA PATHOGENESIS

AG Gadjigoroyeva, MI Lukashina* Public Institution- Central Scientific Research Dermatovenereologic Institute (Russia); *N.N. Blokhin Russia’s Scientific Centre of Oncology of the Russian Academy of Medical Sciences.

Study goal: The study of apoptosis in the cellular structures of hair follicles and papillae pili in the patients with patchy alopecia (alopecia areata, AA). Material under study: Scalp samples taken from 9 patients with severe AA and 4 patients with mild (local) AA; scalp samples taken from 5 patients with severe AA after hair growth resulting from the treatment. Method: Apoptotic activity in the cells was detected using the TUNEL method for DNA breaks fixation. Results and discussion: Serial studies demonstrated a great number of cells in apoptosis in the patients with AA prior to and after successful therapy with SADBE irritant. It is likely that the high levels of the epidermal cells’ apoptotic activity found in scalp samples taken from the patients with AA are inherent to the nature of keratinocytes since these cells are characterized by both the high proliferative activity and the high rates of apoptosis. The increased rates of apoptosis can be induced by external and endogenous stimuli. Cytotoxic T lymphocytes and cytokines may act as external stimuli while the endogenous stimuli are cell selection within cell population (elimination of cells with genetic defects) and irreparable DNA breaks followed by the chain of activational apoptosis reactions. Persistence of elevated apoptosis in keratinocytes after hair growth can be explained by epidermal cells immaturity resulting from the increase in their mitotic activity following the therapy. Cell apoptosis is a dynamic system and, if the stages after which apoptosis becomes irreversible have not been reached yet, it can be reversed. This study demonstrated the high rates of apoptosis readiness of hair follicle keratinocytes in AA. However the method used in this study does not allow to distinguish between TUNEL-fixed cells with DNA breaks and those in which apoptosis became irreversible. This problem requires further investigation. Detection of specific markers will allow to study the mechanisms of apoptosis in AA which will facilitate further investigation of pathogenesis of this disease.