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With emergence of MHC class I tetramers loaded with CD8+ T-cell viral epitopes, it is possible to study virus-specific CD8 cells in humans during infection and after vaccination. MHC class I tetramers was used to detect the frequency of haemagglutinin (HA)-specific T cells in 26 healthy influenza-vaccinated humans. Peripheral blood was collected before, and 7, 14 and 28 days after vaccination. Four-colour flow cytometry was used for monitoring of vaccine induced T-cell response. In 15 donors, two- to fivefold increase in frequency of HA-specific T cells was observed 7 days after vaccination. In addition, in 12 of these donors, this increase was accompanied with fourfold increase of H1N1 antibody titre. The increase in frequency of HA-specific CD8+/IFN-γ+ cells was low and peaked 28 days after vaccination in three of the six donors tested. Frequencies of HA-specific CD8+ T cells and antibody titre returned to prevaccination values 1 year after vaccination. Subunit influenza vaccines have the ability to induce HA-specific CD8+ cells. As the immune response to this vaccine decreased significantly after 1 year, our results confirm the importance of annual immunization for adequate protection. [ABSTRACT FROM AUTHOR]

With emergence of MHC class I tetramers loaded with CD8+ T-cell viral epitopes, it is possible to study virus-specific CD8 cells in humans during infection and after vaccination. MHC class I tetramers was used to detect the frequency of haemagglutinin (HA)-specific T cells in 26 healthy influenza-vaccinated humans. Peripheral blood was collected before, and 7, 14 and 28 days after vaccination. Four-colour flow cytometry was used for monitoring of vaccine induced T-cell response. In 15 donors, two- to fivefold increase in frequency of HA-specific T cells was observed 7 days after vaccination. In addition, in 12 of these donors, this increase was accompanied with fourfold increase of H1N1 antibody titre. The increase in frequency of HA-specific CD8+/IFN-gamma+ cells was low and peaked 28 days after vaccination in three of the six donors tested. Frequencies of HA-specific CD8+ T cells and antibody titre returned to prevaccination values 1 year after vaccination. Subunit influenza vaccines have the ability to induce HA-specific CD8+ cells. As the immune response to this vaccine decreased significantly after 1 year, our results confirm the importance of annual immunization for adequate protection.

Aim: To analyze the distribution of lymphocyte subsets in the peripheral blood of patients with infectious mononucleosis caused by Epstein-Barr virus (EBV) and cytomegalovirus (CMV) and to investigate the possible diagnostic usefulness of flow cytometry panel recommended by the Center for Disease Control and Prevention (CDC) for HIV-1 infection., Methods: The study included 130 immunocompetent adults with infectious mononucleosis caused by EBV (n=103) and CMV (n=27) and 50 controls. EBV-infected patients were divided into two groups based on typical (n=92) or atypical (n=11) clinical presentation of the disease. Lymphocyte subpopulations were determined by flow cytometry and a panel of monoclonal antibodies recommended by the CDC for the immunophenotyping of patients infected with human immunodeficiency virus (HIV)., Results: Patients with typical and atypical presentation of EBV-induced infectious mononucleosis showed increased percentages of total T-cells, cytotoxic-suppressor CD8(+) T cells and activated HLA-DR(+) T cells compared to healthy controls. Percentages of CD4(+) T cells, as well as CD4/CD8 ratio, were significantly decreased. Absolute counts of CD4(+) T cells and percentages of B cells did not differ from healthy controls. Pattern of changes in CMV-infected patients was completely identical to that in healthy controls, although less pronounced., Conclusion: Lymphocyte subpopulations represented in the CDC panel for HIV are sufficient for the recognition of patients with infectious mononucleosis caused by EBV and CMV. Flow cytometry can be useful support for reaching diagnosis in patients with atypical clinical presentation of EBV-induced infectious mononucleosis.