The MDS Beacon™

A recent study showed that flow cytometry, a test already established to accurately diagnose myelodysplastic syndromes (MDS), can also help identify the causes of cytopenia.

Cytopenia is a condition characterized by unusually low blood cell counts and is routinely identified by blood tests. Bone marrow examinations are usually required to determine whether MDS is the cause of the cytopenia. However, some patients have inconclusive bone marrow examinations and require more sensitive tests, such as flow cytometry, to establish or exclude a diagnosis of MDS.

A flow cytometry test requires collecting a sample of bone marrow cells from the patient. The sample is treated with antibodies that are marked with fluorescent dyes. These antibodies bind to cells that contain specific cellular markers. A laser is then used to detect and count the cells that give off light, indicating the presence of these markers. Because normal development of blood cells produces known levels of specific cellular markers, samples that have abnormal amounts will give off light at different intensities. In this study, dye intensities resulting from more than five abnormalities were assigned a positive flow cytometry score. An intermediate score indicated three or four abnormal markers, while two or fewer irregularities were given a negative score.

The study tested 102 cytopenic patients whose bone marrow examinations did not show clear signs of MDS, such as abnormally shaped and defective blood cells or immature cells that accumulate in the bone marrow.

A positive flow cytometry value was found in 21.6 percent of patients, a negative value in 67.6 percent, while the remaining 10.8 percent had an intermediate flow cytometry value. During the median 11 month follow-up period, cytopenia was attributed to MDS or another bone marrow disease in 11.8 percent of patients, a different medical condition in 59.8 percent, and was indeterminate in 28.4 percent.

Results showed a high correlation between flow cytometry score, an indication of the severity of irregular blood cell development, and the cause of cytopenia. Specifically, 41 percent of patients with a positive flow cytometry result were later diagnosed with MDS or a related bone marrow disease, and another 41 percent remained undiagnosed. Furthermore, 97 percent of patients with negative scores, indicating few developmental abnormalities, were able to attribute their cytopenia to another condition or remained undiagnosed.

Researchers concluded that flow cytometry may become more useful in diagnosing MDS in cytopenic patients who have initially inconclusive bone marrow examinations.

For more information, please see the related research article in Leukemia Research (abstract).