Clinical applications of flow cytometry. Immunologic methods for measuring cell membrane and cytoplasmic antigens.

Flow cytometric analysis is the method of choice for classifying leukemia and lymphomas. When combined with other clinical and morphometric data, a definitive diagnosis can be made in the most difficult cases. By using a combination of specific antibodies that are each labeled with a different fluorochrome, panels can be designed to follow residual disease with greater precision than any other method. The detection of intracellular proteins is less well developed. Because antibodies can bind nonspecifically to dead cell components, there may be considerable biological noise. This noise reduces the sensitivity for detecting the desired protein within the cell. Until this problem is solved, it is likely that other methods may provide more reliable data. The major advantages of flow cytometry are rapid cell processing, cell by cell analysis, and the simultaneous evaluation of multiple markers. The latter is especially important because more tests can be performed using less clinical material. When flow cytometric results are combined with histologic results, the confidence in professional interpretation is far greater than either can provide alone. It is likely that the future application of these approaches will significantly improve diagnosis and patient care.