Dopa-stained melanocytes in the macular lesions of early leprosy

Sérgio Luiz Gomes Antunes; Samantha Lee Salgueiro Alves; Suzana Corte-Real; Maria Nazaré Meireles; José Augusto da Costa Nery; Euzenir Nunes Sarno

doi:10.47878/hi.1996.v21.36475

Authors

Sérgio Luiz Gomes Antunes Leprosy Laboratory - Oswaldo Cruz Institute - Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brasil.
Samantha Lee Salgueiro Alves Leprosy Laboratory - Oswaldo Cruz Institute - Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brasil.
Suzana Corte-Real Department of Ultrastructure and Cellullar Biology, Oswaldo Cruz Institute
Maria Nazaré Meireles Department of Ultrastructure and Cellullar Biology, Oswaldo Cruz Institute
José Augusto da Costa Nery Leprosy Laboratory - Oswaldo Cruz Institute - Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brasil.
Euzenir Nunes Sarno Leprosy Laboratory - Oswaldo Cruz Institute - Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brasil.

DOI:

https://doi.org/10.47878/hi.1996.v21.36475

Abstract

The mechanism of association of hypopigmentation and sensorial loss in a leprosy macular lesions has not been clarified yet. The biopsy of a macular lesion on the medial face of the right forearm of a fourteen-year old male leprosy patient was submitted to DOPA-staining for
melanocytes, which is specific for the melanocytic tyrosinase enzyme and it is a proper method for identifying and counting these cells in the skin. A contralateral specimen of the same patient went through the same procedure as a control experiment. The specimen from the macular lesion
showed a higher number of DOPA-stained melanocytes than the control fragment. Dermal melanocytes were present in high amounts in the abnormal specimen. Increased expression of tyrosinase by melanocytes in the macular lesions may reflect a positive feed-back stimulus
represented by the lack of substrate tyrosine, which may in turn be utilized by the mycobacterial agent. Ultrastructural study of the normal and pathological specimens showed no significant differences in the morphological appearance of melanocytes and their melanosomes. These results suggest that the utilization of phenolic compound by the Mycobacterium leprae may be involved in the mechanism of hypopigmentation. A higher number of cases will be necessary to confirm this hypothesis.

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