An overview of the use of flow cytometry in the analysis of mixed red cellpopulations

This paper reviews the application of flow cytometric techniques to the ana lysis and quantitation of mixed red cell populations. Such mixtures may ari se in a variety of ways, for example: through transplacental hemorrhage dur ing pregnancy or upon delivery; through iatrogenic procedures such as blood transfusion, bone marrow or peripheral blood stem cell transplantation; or through disease, when a loss of surface antigen expression may occur due t o the expansion of abnormal progenitors lacking the appropriate gene or lac king the ability to translate the product of the gene. Flow cytometry can o ffer a simple and accurate means of identifying and quantitating mixed red cell populations through detection of antigens specific for either donor or recipient, and in many cases it is possible to distinguish homo- or hetero zygous expression of a common antigen. Internal antigens may be accessed af ter fixation and permeabilisation of the red cells. These latter techniques are relatively new and expand the spectrum of antigenic differences availa ble for the identification of individual species in mixed populations.