Lymphocyte surface antigens in the peripheral blood. Detection by flow cytometry. Applications to the immune system in clinical practice

A flow cytometer enables observation of single cells providing morphological characterization of the cell and identification of cell markers. The cells pass a detection point where they are striked by a sharply focused beam. Light scattering by the cells gives informations about size and granularity. Detection of fluorescence emission permits identification of fluorescent tag such as antibodies. Flow cytometric analysis of immunologic phenotyping allows interpretation of weak fluorescence intensity and detection of two antigens on a single cell with dual fluorescence analysis. Evaluation of B and T cells and their subclasses from whole blood preparations, provides informations of immunological status. Immunophenotyping at the clinical level has been used in a variety of human diseases; immunophenotypic changes have been observed in congenital and acquired immunodeficiency syndromes and auto-immune disorders.