Comparative analysis of immunological characteristics of patients with mild and severe influenza A（H1N1）
Objective To comparatively analyze the immunological characteristics of patients with mild and severe influenza A （H1N1）, and to provide the evidence for condition monitoring and treatment . Methods 52 cases with mild influenza A （ H1N1）, 152 cases with severe influenza A （ H1N1） and 26 healthy subjects from July 1, 2009 to December 31, 2009 were enrolled in the study.Lymphocyte subsets in peripheral blood were analyzed by flow cytometry and the serum concentrations of interferon -γ（ IFN-γ） and interleukin-4 （IL-4） were detected by enzyme-linked immune-sorbent assay （ELISA）.Results The total lymphocyte counts were decreased obviously in patients with severe influenza A （ H1N1） than in mild pa-tients and in healthy subjects （P0.05）.Con-clusion Immune dysfunction in patients with influenza A （H1N1） infection is associated with the severity of disease, especially cellular immunity .Therefore, monitoring of the immune system is valuable for the diag-nosis of influenza A（H1N1） infection. 
 
Key words: 
Influenza A virus,H1N1 subtype; Lymphocyte subsets; Interferon-γ; Interleukin-4