Flow cytometry: its applications to immunohaematology.

Flow cytometry, using fluorescent probes, has only recently been applied to practical aspects of immunohaematology. It has been used for the detection and quantitation of cell-bound immunoglobulins and complement, minor cell populations, cellular antigens, and platelet and granulocyte antibodies. Practical applications of detecting minor cell populations have been successful in determining the extent of fetal maternal haemorrhage; determining the survival of transfused RBCs (small and large volumes); demonstrating RBC chimaerism (e.g. following bone marrow transplantation) and RBC mosaicism (e.g. demonstration of the McLeod phenotype carrier status). A large variety of cellular antigens have been demonstrated on RBCs, platelets and white cells using flow cytometry. Quantitation of RBC antigens by flow cytometry has been found to be much more objective and accurate than the routinely used serological approaches for establishing zygosity in paternity studies. Flow cytometry has been found to be a sensitive, objective and reproducible method for detecting platelet auto-and alloantibodies, and has also been used to detect granulocyte antibodies. More recently, it has been used to detect antibodies to monocytes and lymphocytes. As flow cytometers become more commonly available, many of these applications may become routine in clinical pathology laboratories.