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Leprosy (leprosy): what's going on?
Last reviewed: 23.04.2024
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The development of various morphoclinic types of leprosy caused by the same pathogen is due to the peculiarities (level) of T-cell immunity, the ability of HRT reactions to M. Leprae antigens . When the cellular immune response is incompetent in combination with the active production of humoral antibodies, a lepromatous type of leprosy develops, and with an intensive cellular response according to the Th1 type, a tuberculoid type of leprosy. Because M. Leprae is an obligate intracellular parasite of the cells of the mononuclear phagocyte system (CMF), the macrophage occupies a central place in the system of immune reactions in leprosy. In the lepromatous type of leprosy, SMP cells are represented by both normal macrophages and large cells containing large amounts of M. Leprae with different degree of vacuolization of the cytoplasm ("leprosy cells" or "Virchov cells"), and in tuberculoid type leprosy, i.e. With malabacterial forms, - epithelioid cells and typical Langhans cells. In the tuberculoid type of leprosy, clear focuses of epithelioid cells are surrounded by a lymphoid curb (tuberculoid tubercle); granuloma reaches the epidermis directly, notes signs of hypersensitivity (deep erosion of the epidermis, thickening and central caseiasis of the skin nerves, fibrinoid necrosis in the dermis, the presence of giant Langhans cells). Small nerves are usually not determined, since they are destroyed or strongly infiltrated. M. Leprae is found with difficulty in the form of single cells in the thickened nerve tissue or they are not detected.
With an undifferentiated form of lepra, the granuloma does not develop, but an infiltrate of a simple inflammatory structure with a large or low content of M. Leprae, located intracellularly , occurs .
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