The MxA protein levels in whole blood lysates of patients with various viral infections

Interferon alpha (IFN alpha), a type I interferon, can be considered as a viral infection marker because this cytokine is induced during many viral infections. However, it is quite difficult to detect IFN alpha in sera. Investigations are interested in various intra-cellular IFN alpha-induced proteins as viral infection markers. However the activity of these enzymes increased not only in response to type I IFNs but also to type II IFN. MxA protein can be detected in the cytoplasm of IFN alpha/beta-treated cells, whereas other cytokines, including IFN gamma, are poor inducers. Using an immunochemiluminescent assay, we studied MxA protein in whole blood of 34 patients with various viral infections. The whole blood was drawn into sterile vacuum tubes containing heparin or EDTA. MxA values were relatively similar in heparin-treated samples and EDTA-treated samples, with differences not exceeding 1 ng/ml. The levels of MxA protein were compared in whole blood obtained by using two different lysis procedures. A correlation was found between the MxA levels obtained by using procedure I and procedure II, but higher amounts of MxA protein were found with procedure II. The second procedure is rapid and more convenient than the other and it is carried out in one step which reduce technical problems. High levels of MxA protein were found in peripheral blood cells of patients with acute viral infections (Rotavirus, Adenovirus, RSV, CMV), but MxA protein was not elevated in bacterial infections. The MxA levels were also studied in peripheral blood of 32 HCV positive patients. MxA protein was not found in most of IFN alpha-untreated patients, even those with high viral load. In contrast, high levels of MxA protein were found in IFN alpha-treated patients. MxA quantitation can be considered as a specific marker of acute viral infections, and could be useful in the management of treatment with IFN alpha. (C) 1998 Elsevier Science B.V. All rights reserved.