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High tumor necrosis factor-α (TNFα) levels were present in the serum of24 of28 active visceral leishmaniasis (VL) patients (142.9 ± 113.9pg/ml, mean ± SD), whereas levels were not elevated in 26 of 30 patients with cryptic leishmanial infection (16 asymptomatic, 4 with self-healing subclinical infection, and 10 posttreatment VL cases). Serum TNFα levels were also not elevated in 15 normal volunteers (11.3 ± 15.6 pg/ml) and in 10 patients with tegumentary leishmaniasis (19.1 ± 10.8pg/ml). Leishmanial infection of human monocyte-derived macrophages enhanced the basal TNFα production by these cells, and this effect was further potentiated by treatment with recombinant interferon-γ, After effectivetreatment ofVL patients, serumTNFα levelsdropped rapidly (129 ± 112 vs. 9 ± 13 pg/ml in 10 days), even before clinical parameters such as spleen size or parasitism, white blood cell count, or levels of hemoglobin returned to normal values. On the other hand, patients unresponsive to treatment remained with elevated levels (276 ± 69 vs. 155 ± 71 pg/ml in 10 days). Thus, serum TNFα levels in VL patients are a good parameter to monitor in determining host response to therapy. [ABSTRACT FROM PUBLISHER]

The induction of endogenous interferon (lFN) was studied in 28 cases of Argentine hemorrhagic fever (AHF), a severe systemic disease caused by Junin virus. Serum samples were taken daily during the acute period, both before and after administration of immune plasma. This form of treatment has been found to reduce mortality when given early in the course of AHF. High titers of circulating IFN were present in the serum samples taken before treatment. IFN titers drastically dropped after transfusion of immune plasma. The antiviral activity was stable at pH 2 and was completely neutralized only by antibodies against IFN-α. Thus, we concluded that circulating endogenous IFN in patients with AHF can be considered as typical IFN-α. Fever, chills, and backache were associated with the higher levels of IFN. An inverse correlation between days of evolution of the disease and IFN activity was also observed. [ABSTRACT FROM PUBLISHER]

Interferon was induced by infecting mice with Brucella suis. Serum containing interferon activity was analyzed by chromatography on Concanavalin A-Sepharose and Phenyl-Sepharose CL-4B columns. Antiviral activity was completely retained by the lectin column indicating that all the interferon molecules are glycosylated. The chromatographic behaviour of Brucella interferon on Phenyl-Sepharose CL-4B shows that, like other interferons, Brucella interferon displays hydrophobic properties. However, the hydrophobicity of the interferon molecule was masked in the crude preparation and was only detectable when purified Brucella interferon was used for chromatography. The antigenic properties of Brucella interferon provided the means for developing an affinity chromatographic method resulting in about 60,000 fold purification. As in the case of viral interferon, treatment of L cells with Brucella interferon induced specific enhanced in vitro phosphorylation of a 67,000 molecular weight protein after incubation of cell extracts with double-stranded RNA and [γ-P] ATP. [ABSTRACT FROM AUTHOR]