IMMUNOHISTOCHEMICAL DEMONSTRATION OF MYCOBACTERIUM LEPRAE IN THE NERVOUS SYSTEM OF LONG-TERM CURED LEPROSY PATIENTS USING A M. LEPRAE SPECIFIC ANTI-PGL ANTIBODY

Leprosy (Hansen's disease) has become a curable disease by the advance of chemotherapy, however, deformities evoked by nerve damages are still a great problem of treatment. We have recently demonstrated a highly sensitive and specific method to identify the leprosy antigen in skin tissue by immunohistochemical staining using a Mycobacteriam leprae-specific antiphenolic lipid-I (PGL) monoclonal antibody. Using this method, we have examined the peripheral nerves of lower extremities, spinal cords and brain stems of clinically cured (skin slit smear negative more than 10 years) leprosy autopsy cases (Lepromatous (L) : n= 6, Tuberculoid (T) : n= 6), in which ordinary Fite's acid-fast staining did not reveal M. leprae. Positive staining was observed as follows : (1) Peripheral nerves : L : 6/6, T : 1/6. (2) Dorsal root ganglia and posterior spinal roots : L : 6/6, T : 2/6. (3) Anterior roots : L : 0/6, T : 0/6. (4) Spinal cord : L : 6/6, T : 2/6, observed in posterior horn cytoplasm and anterior horn neurons. (5) Medulla oblongata : L : 6/6, T : 2/6, observed mainly in ambiguus, facial, hypoglossal, cuneate and gracile nuclei. These findings indicate that M. leprae specific antigen remains in the peripheral sensory nerves as well as central sensory and motor nerves long after the clinical cure, especially in lepromatous patients where definitely abnormal cellular immunity against M. leprae is noted, which suggest the role of motor neurons in the pathogenesis of quiet nerve paralysis.