title: Apoptosis of lymphocytes and monocytes infected with influenza virus might be the mechanism of combating virus and causing secondary infection by influenza.
abstract: Influenza affects most of the world's population annually, often causing a secondary infection, but pathological mechanisms of influenza virus infection remain unclear. We have found that influenza viruses have a selective preference for infecting monocytes and mature immune effector cells. This paper provides evidence that influenza virus infection increases the expression of granzyme B (GrB) in monocytes, activated T and B cells. All GrB(+) cells had cytolytic function. GrB(+)CD62L(high) central memory (T(CM)) cells were fast response population to virus infection when compared with GrB(+)CD62L(low) population. The influenza virus-infected PBMC could be killed by GrB(+) cells. We propose the following mechanism for influenza: (i) influenza virus within the respiratory tract overcomes humoral defenses; (ii) free virus is directly engulfed by the immune system effector cells and free virus also infects epithelial cells; (iii) virus-infected epithelial cells and the immune system cells are killed by cytotoxic cells. These indicated that an immune system that was combating a virus infection needs to sacrifice some of its immune system cells. Therefore, influenza viruses might temporally destroy the human immune system's line of defense, resulting in susceptibility to a secondary infection. This might be a prevalent mechanism existing in cell-mediated immune responses.
authors.affiliation: Department of Hematology, Lanzhou General Hospital, Gansu, China. xiedx@hotmail.com
authors.forename: Dongxu
authors.initials: D
authors.lastname: Xie
authors.forename: Hai
authors.initials: H
authors.lastname: Bai
authors.forename: Lihua
authors.initials: L
authors.lastname: Liu
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Xie
authors.forename: Janet
authors.initials: J
authors.lastname: Ayello
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Ma
authors.forename: Junying
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000821:virology; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology / Q000821:virology; D053804:Granzymes / Q000378:metabolism; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000821:virology; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000821:virology; D010950:Plasma Cells / Q000276:immunology / Q000821:virology; D013601:T-Lymphocytes / Q000276:immunology* / Q000821:virology
chemical_list: D053804:Granzymes