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Purpose: Hemostatac alterations and elevated tumor necrosis factor/eachectin (TNF alpha) serum levels may contribute to the pathogenesis of organ complications in human Plasmodium falciparum malaria. Therefore, we examined whether altered protein C (PC) and thrombin-antithrombin III (TAT) plasma levels correlated with TNF alpha serum concentrations, parasitemia, and the clinical course of human P. falciparum malaria. PATIENTS AND METHODS: Forty-seven patients with P. falciparum malaria were evaluated prospectively before and during antiparasitic therapy. TNF alpha serum levels were determined by immunoradiometric assay, PC and TAT plasma antigen by enzyme-linked immunosorbent away, and PC and PC inhibitor-1 (PCI-1) activity levels by functional tests. Cultured endothelial cells were incubated with serum from four patients with malaria and from healthy control subjects and then assayed for procoagulant activity. Northern blot hybridization was used to detect tissue factor mRNA. RESULTs. In vivo, TNF alpha serum concentrations were elevated (median: 38.6 pg/mL; n = 47) while plasma levels of PC (antigen 55A%; activity 39.0%; n = 47) and PCI-1 (0.56 U/L) were decreased in almost all patients before antiparasiic treatment. At the same time, TAT concentrations were high. These alterations correlated significantly (p CONCLUSION- Elevated levels of TNF alpha and TAT, decreased plasma levels of anticoagulant PC, and the induction of procoagulant activity in endothelial cells by patient serum indicate a shift in the balance of hemostatic activity towards a procoagulant state in P. falciparum malaria. The alterations in TNFA, TAT, and PC levels may be a response to infection, since they correlate with parasitemia and are reversed during antiparasitic treatment., Malaria is an infectious disease caused by the parasite Plasmodium. Infection with Plasmodium falciparum is associated with an increase in the number of platelets (cells involved in blood clotting) and changes in blood flow that promote coagulation. These effects may be due to tumor necrosis factor/cachectin (TNF alpha), which is a cytokine, or growth-regulating factor. TNF-alpha was shown to reduce levels of protein C (PC), which prevents blood coagulation, and increase levels of a protein that enhances blood coagulation. The relation between the severity of P. falciparum malaria, parasitemia (the presence of parasites in the blood) and hemostatic (blood flow-related) changes was assessed in 47 patients with P. falciparum malaria. The levels of certain factors that control blood coagulation were measured, including the anticoagulant PC and several factors that enhance coagulation: coagulation factor IX, TNF-alpha, and thrombin-antithrombin III(TAT). Before treatment with antimalarial agents, the blood levels of TNF-alpha and TAT were increased, whereas the levels of PC and its inhibitor, referred to as PCI-1, were decreased. These trends were correlated with the severity of malaria and number of parasites in the blood. However, coagulation factor IX was not changed. When endothelial cells, which line the surface of some tissues, were exposed to the blood of a patient with severe malaria under laboratory conditions, the coagulation activity and genetic material that codes for coagulant factors in the endothelial cells increased. These findings show that P. falciparum infection results in the development of conditions that enhance blood coagulation. The changes in blood flow may be a reaction to P. falciparum infection, because hemostatic changes are correlated with the number of parasites in the blood and can be restored to normal conditions by antimalarial therapy. (Consumer Summary produced by Reliance Medical Information, Inc.)

PURPOSE: Tumor necrosis factor alpha (TNF-alpha) has been implicated in the pathology of experimental malaria. To establish its relevance to human malaria, we studied serum levels of two monocyte-derived cytokines, TNF-alpha and interleukin-6 (IL-6), as well as of the lymphocyte-derived mediator interferon gamma (IFN-gamma) in patients with malaria before and during antiparasitic treatment. PATIENTS AND METHODS: One hundred twenty serum samples of 40 patients with malaria (Plasmodium falciparum [n = 32], Plasmodium vivax [n = 8]) were analyzed. IL-6 was measured by a highly sensitive and specific bioassay, TNF-alpha by immunoradiometric assay, and IFN-gamma by radioimmunoassay. RESULTS: Elevated cytokine levels could be detected in the majority of patients with P. falciparum malaria before treatment (31 of 32, 21 of 32, and 21 of 32 for TNF-alpha, IL-6, and IFN-gamma, respectively), but only in some patients with P. vivax malaria (four of eight, one of eight, and zero of eight for TNF-alpha, IL-6, and IFN-gamma, respectively). Serum concentrations of the monokines TNF-alpha and IL-6 correlated significantly with parasitic density (p

ABSTRACTOrgan failure in Plasmodium falciparummalaria is associated with neutrophil activation and endothelial damage. This study investigates whether neutrophil-induced endothelial damage involves apoptosis and whether it can be prevented by neutralization of neutrophil secretory products. Endothelial cells from human umbilical veins were coincubated with neutrophils from healthy donors and with sera from eight patients with P. falciparummalaria, three patients with P. vivaxmalaria, and three healthy controls. Endothelial apoptosis was demonstrated by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and annexin V staining. The rate of apoptosis of cells was markedly increased after incubation with patient serum compared to that with control serum. Apoptosis was most pronounced after incubation with sera from two patients with fatal cases of P. falciparummalaria, followed by sera of survivors with severe P. falciparummalaria and, finally, by sera of patients with mild P. falciparumand P. vivaxmalaria. Ascorbic acid, tocopherol, and ulinastatin reduced the apoptosis rate, but gabexate mesilate and pentoxifylline did not. Furthermore, in fatal P. falciparummalaria, apoptotic endothelial cells were identified in renal and pulmonary tissue by TUNEL staining. These findings show that apoptosis caused by neutrophil secretory products plays a major role in endothelial cell damage in malaria. The antioxidants ascorbic acid and tocopherol and the protease inhibitor ulinastatin can reduce malaria-associated endothelial apoptosis in vitro.

Elevated serum or plasma concentration of immunoreactive tumor necrosis factor (TNF) is consistently detected in patients with malaria. TNF levels correlate with high parasitemia and clinical severity but not always with outcome. Since the effects of TNF may be neutralized by soluble TNF receptors, sera of 30 nonimmune patients with malaria were analyzed before and during antimalarial therapy. High concentrations of receptors R1 (55 kDa) and R2 (75 kDa) were detected immunologically in all sera of untreated patients. Levels of immunoreactive TNF correlated closely with levels of soluble TNF R1 and R2 (r = .75 and .59, respectively). In contrast, sera lacked cytotoxic activity against target cells in the TNF bioassays. Soluble TNF receptor levels remained elevated for days after treatment. These results suggest that excessive release of TNF induced by the asexual stage of malaria parasites is controlled by a subsequent shedding of soluble TNF receptors that may bind and deactivate biologically functional TNF.