Center for Disease Control (CDC) flow cytometry panel for human immunodeficiency virus infection allows recognition of infectious mononucleosis caused by Epstein-Barr virus or cytomegalovirus.

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.

[MHC tetramers: tracking specific immunity]. / MHC-tetrameri: na tragu specificnoj imunosti.

In an adaptive immune response, antigen is recognized by two distinct sets of highly variable receptor molecules: (1) immunoglobulins, that serve as antigen receptors on B cells and (2) the antigen-specific receptors on T cells. T cells play important role in the control of infection and in the development of protective immunity. These cells can also mediate anti-tumor effects and, in case of autoimmune syndromes, contribute to the development and pathology of disease. The specificity of T cells is determined by T cell receptors (TCR). Understanding of the success of immune responses requires the direct measurement of antigen-specific T lymphocytes. Cell with major histocompatibility complex (MHC) class I molecules are able to present antigens to antigen-specific CD8+ cytotoxic T lymphocytes. MHC class I molecules present small peptides (epitopes) processed from intracellular antigens such as viruses and intracellular bacteria. MHC class I molecules in humans are designated as human leukocyte antigen (HLA) class I and divided into HLA-A, -B and -C. CD8+ T cells recognize MHC class I molecules and after activation produce proteins that destroy infected cells. MHC class II molecules receive their peptides mainly from extracellular and soluble antigens and present them to the CD4+ T helper cells. A recently described technique that can be used in flow cytometry enables us to quantify ex vivo antigen-specific T cells by binding of soluble tetramer MHC-peptide complexes attached to fluorochrome. Quantitative analyses of antigen-specific T cell populations provide important information on the natural course of immune responses. The interaction of T cell receptors on T lymphocytes with tetrameric MHC-peptide complexes mimics the situation on the cell surface, and allows for reliable binding. Tetramers consist of four biotinylated HLA-peptide epitope complexes bound to streptavidin conjugated with fluorescent dye. Tetramer technology has sensitivity of detection as little as 0.02% of total cytotoxic T cell pool or T helper cell pool (i.e. approximately 1 in 50.000 lymphocytes). The combination of this technology with intracellular cytokine staining methods opens up significantly better ways of studying these cells than previously possible, allowing immunologists to look at their life cycle (activation and proliferation), manner of death (aging and apoptosis) and effector function (cytotoxic potential and cytokine production). MHC tetramers class I have yielded useful insights into in vivo dynamic and function of antigen-specific CD8+ T cells in viral infections, parasitic infections, cancer, autoimmune disease and transplantation. This knowledge is of special interest for immunotherapy, diagnostic monitoring of T cell mediated immunity, and the development of new vaccination strategies. There is some possibility for cell therapy with antigen-specific CD8+ T cells for various diseases including cancer and viral infections. Targeted immunotherapy of selective deletion of auto--or alloreactive T cells with MHC tetramers may be important for the treatment of autoimmune disease, or to prevent the rejection of transplanted organs. The utility of this technique for the immunotherapy in vivo needs to be confirmed and modified in further research. Understanding how antigen-specific cells develop and function in different circumstances and pathologies will be the key to unravelling the secrets of cellular immune system.