Human Macrophage Tumor Necrosis Factor (TNF)–α Production Induced byTrypanosoma brucei gambienseand the Role of TNF‐α in Parasite Control

Abstract

Trypanosoma brucei gambiense a causative agent of sleeping sickness, induced a dose-dependent production of tumor necrosis factor (TNF)–α by human macrophages in vitro. TNF-α was also induced in the Mono Mac 6 cell line, which indicates a direct effect of parasite components on macrophages. Parasite-soluble factors were also potent inducers of TNF-α. The addition of anti–TNF-α to cocultures of macrophages and parasites increased the number of trypanosomes and their life span, whereas irrelevant antibodies had no effect. TNF-α may have a direct role (i.e., direct trypanolytic activity) and/or an indirect one, such as TNF-α–mediated induction of cytotoxic molecules. A direct dose-dependent lytic effect of TNF-α on purified parasites was observed. This lytic effect was inhibited by anti–TNF-α. These data suggest that, as in experimental trypanosomiasis, TNF-α is involved in parasite growth control in human African trypanosomiasis