The paper aimed to investigate the differences in immunological evaluations between influenza type A H1N1 virus-infected patients and uninfected individuals. T-cell subtypes in peripheral blood from 32 H1N1-infected patients were quantified using flow cytometry. Specific protein markers in serum were determined and blood cells were counted. The results showed thatmean counts of CD3⁺ , CD3⁺ CD4⁺ , and CD3⁺ CD8⁺ T cells in peripheral blood of H1N1-infected patients were significantly reduced compared with those in uninfected individuals whereas serum complement components ( C3 and C4) and C-reaction protein were significantly increased in H1N1-infected patients. Furthermore, platelets, leukocytes, lymphocytes, and eosinophilic cells were significantly decreased, while monocytes were significantly increased in this population. It is indicated that routine immunological evaluation has
clinical significance in H1N1-infected patients.