Clinical examination
The clinical data of each subject was collected from the hospital records. These data included age, sex, and laboratory tests. Individual subjects were subjected to routine laboratory tests for full blood cell counts, C-reactive protein (CRP), erythrocyte sedimentationrate (ESR), N-terminal pronatriuretic peptide (NT-proBNP), and the concentrations of serum immunoglobulins (Ig)G, M, A and complement (C)3, 4 by a biochemistry automatic analyzer (Roche Diagnostics, Branchburg, USA) and scatterred turbidimetry on a Siemens special protein analysis instrument (Siemens Healthcare Diagnostics Products, GmbH, Germany).