Interleukin-10-dependent down-regulation of interferon-gamma response to Leishmania by Mycobacterium leprae antigens during the clinical course of a coinfection
A 46-year-old male patient presented with a clinically active mucosal leishmaniasis and lepromatous leprosy coinfection, the clinical picture of which has been previously described in detail (). The diagnosis of polar lepromatous leprosy was based on positive results from smears of skin samples from the earlobes, elbows, and knees, with an average bacterial index of 4+ with Ziehl-Nielsen staining. Mucosal leishmaniasis was diagnosed by isolation of Leishmania from the nasal mucosal lesion. The isolated parasites were characterized as Leishmania braziliensis by isoenzyme analysis (). The patient was treated for leishmaniasis with meglumine antimoniate for 30 days with a low-dose schedule of 5 mg/kg per day of pentavalent antimony and for leprosy with a multidrug therapy regimen () with 24 monthly supervised doses. Leprosy treatment was started 10 months before the beginning of leishmaniasis therapy and ended 13 months after its completion. Nine months after diagnosis, the leishmaniasis lesion was considered to be healed, leaving partial mutilation of the nose. Relapse was noticed 13 months after cure of the mucosal lesion, with erosion of the nose and large edema and infiltration of the nose and lips extending to the malar region. On that occasion, Leishmania parasites were again isolated from a biopsy specimen from the nasal lesion, but the patient had no clinical sign of leprosy and skin smears obtained bilaterally from earlobes, elbows, and knees showed a bacterial index of 0 (zero).