DEMONSTRATION OF MYCOBACTERIAL ANTIGENS IN SKIN BIOPSIES FROM SUSPECTED LEPROSY CASES IN THE ABSENCE OF BACILLI

Skin-biopsies from fifty-six patients suspected of early leprosy from Bahia State, Brazil, were examined histopathologically. The Fite-Farac o staining failed to demonstrate acid-fast bacilli in this material. T he prominent features of the lesions were inflammation of the neurovas cular bundles and sometimes inflammation of the skin appendages. The n on-specific infiltrate was predominantly composed of histiocytes and l ymphocytes. In 41 cases (73.2 %) epidermal atrophy was also present. T he avidin-biotin peroxidase technique was used with primary antibodies to detect bacillary antigens (anti-BCG serum) and nerve branches (ant i-S-100 protein serum). Immunohistochemical detection of bacillary ant igens using the anti-BCG serum was positive in 28 cases (50 %). A posi tive staining for S-100 protein was observed in 40 cases (71.4 %) in d endritic antigen-presenting cells of the skin. The detection of bacill ary antigens, together with the clear demonstration of nerve bundles e nhanced our capacity to fulfill morphologic criteria for the diagnosis of early leprosy. Our observations indicate that the use of immunohis tochemical methods represent a useful tool for the early diagnosis of leprosy.