MALARIA - A TUMOR-NECROSIS-FACTOR INHIBITOR FROM PARASITIZED ERYTHROCYTES

The excessive production of tumour necrosis factor (TNF) is associated with the pathology of blood-stage malaria and phosphatidylinositol-co ntaining phospholipid antigens from parasitized erythrocytes stimulate its secretion by macrophages, thus acting as toxins. This brief repor t describes some properties of an inhibitor present in lysates from er ythrocytes infected with malarial parasites that blocked the detection of recombinant TNF in an enzyme-linked immunosorbent assay and dimini shed or abolished the cytotoxicity of TNF. It was not found in control lysates of normal erythrocytes. Its addition to macrophage cultures s timulated by toxic malarial preparations or by bacterial lipopolysacch aride also blocked the detection of TNF. These findings may explain th e contradictory results obtained from different assays for TNF, and em phasize the need for caution when interpreting the results of a single assay system. If released when parasitized erythrocytes rupture in vi vo, the inhibitor could help protect both parasite and host from the d amaging effects of TNF.