Flow cytometry in transfusion medicine: Development, strategies and applications

Nowadays, flow cytometry represents an essential tool for the daily work in laboratories for transfusion medicine. After cytophotometry of immobilized cells, flow cytometry was developed since the 1960s using moving fluorescence-stained cells. This technique enabled the determination of several thousand cells per second, e. g. from blood, bone marrow, or organ-associated cell suspensions. The introduction of monoclonal fluorescence-labeled antibodies in diagnostics has further accelerated the development of flow cytometry. In the meantime, numerous cellular and nuclear properties can simultaneously be measured on single cell level in automated devices at high speed and precision. Internal standards and quality control systems further increased the accuracy of flow cytometric analyses. Flow cytometry is therefore likewise suitable for routine diagnostics in patients, quality control of blood components and scientific purposes in transfusion medicine. Nevertheless, many flow cytometric applications are related to counting of rare events or detection of cells with low antigen expression. Therefore, several pre-analytic and analytic factors ( e. g. erythrocyte lysing procedures, cell gating strategies, etc.) may essentially affect the accurate determination of cell numbers and functions. In this issue, TRANSFUSION MEDICINE AND HEMOTHERAPY starts a recurrent sequence of reviews focused on 'Flow Cytometry in Transfusion Medicine'. In order to introduce the flow cytometry series, this review summarizes the development, principles, and strategies of flow cytometry as an increasing diagnostic tool in medical laboratories. Also, current and possibly future flow cytometric applications in transfusion medicine are epitomized, e. g. quality control of blood products, immunohematologic diagnostics, hematopoietic progenitor cell transplantation, adoptive immunotherapy, and further therapeutic applications. In following issues of this journal, reviews of notable authors will then focus on special applications and give more detailed insights into single diagnostic fields.