In vitro tumor necrosis factor production by mononuclear cells from lepromatous leprosy patients and from patients with erythema nodosum leprosum.

The production of tumor necrosis factor (TNF) by Mycobacterium leprae-stimulated phagocyte cells, isolated from lepromatous leprosy patients (LL) and normal individuals, was evaluated, using the highly TNF-sensitive mouse fibrosarcoma cell line WEHI164cl13. Mononuclear cells, isolated from all individuals studied, showed a low level of spontaneous TNF production, except for patients undergoing erythema nodosum leprosum (ENL), in which we found significantly higher levels of TNF. Addition of M. leprae to the phagocyte cell culture enhanced TNF production in all groups studied, except in the group with untreated leprosy patients. Strongest M. leprae-induced TNF release was found in mononuclear cell cultures derived from ENL patients. Patients in the postreactional state showed significantly higher TNF levels than healthy controls. These findings support the idea that TNF plays a key role in the complex symptomatology of ENL.