Expression of viral antigens after infection of human lymphocytes, monocytes, and macrophages with influenza virus

Previous studies demonstrated that in vitro infection with influenza A viruses altered several functions of human monocytes and macrophages, but did not detectably alter functions of human lymphocytes. For a determination of whether both types of leuko-cytes can be infected by the influenza viruses, human mononuclear leukocytes were in-fected in vitro and assayed for newly produced and cell surface-expressed viral antigens, with use of indirect immunofluorescence techniques and flow cytometry. Infected cells, including both monocytes and lymphocytes, expressed viral hemagglutinin, neuramini-dase, and matrix protein on their surfaces. The expression of influenza virus antigens by such immunocompetent cells may be important in human antiviral defense. Previous studies using human mononuclear leuko-cytes exposed to influenza virus have demonstrated that depressed lymphocyte transformation re-sponses to mitogen stimulation were due to depressed accessory cell function of the macro-phages [1]. However, the macrophages actively pro