We profusely apologize in our response to Adrian Vladutiu for appearing discourteous or callous. Your question struck a particularly sensitive issue which dramatically affects the clinical care of individuals. In the analysis of specimens from patients coming to bone marrow transplant, we have found between 10- 15% have been misdiagnosed based on flow cytometry. These patients have been treated and considered refractory. This is a result of inadequate reagent selection, single parameter analysis or improper gating. We would like to expand on our unfortunate terse response and hope that you and the rest of the flow cytometric community accepts our apology. The ability to operate a flow cytometer does not qualify an individual to perform all types of flow cytometric tests in a clinical setting. Flow cytometry in clinical diagnosis depends on the appropriate use of the instrumentation with attendant quality control as well as proper selection of reagents. Most importantly, there must be an extensive understanding of the normal expression of antigens on the tissue being analyzed. The procedures and approaches used for CD4 enumeration are not adequate for the analysis of complex tissues such as bone marrow, lymph node or body fluids where normal and aberrant cell populations are admixed. The major problem with flow cytometry in a clinical setting is that it always gives data; an answer, a number. Whether or not these data are relevant depends on the operation of the laboratory, the correct procedures and the skill of the technical individual assessing the data. An underlying premise of the Consensus Conference on Flow Cytometry in Leukemia and Lymphoma is that specimens for detection of hematopoietic neoplasms must be run by people who are skilled in this complex analysis and who have been properly trained in assessing the results. It is not proper to accept clinical specimens or to perform clinical tests for which the technologist or pathologist is not properly trained. The suggestion that clinical bone marrow specimens are being submitted to be analyzed by someone who is unskilled in this particular application is not only unacceptable but unethical. Incumbent on the laboratory director and the technologist is the knowledge of where their skills are limited and to refer a specimen to another laboratory for more careful assessment. Specifically, with regards to the analysis of bone marrow, training from other individuals and laboratories is essential. A beginning is the annual flow cytometry clinical course which has a large section on the analysis of bone marrow specimens. Although possible to glean important tactics from published manuscripts, the use of these on a daily basis is best understood when observing the procedures in an operating laboratory. It is necessary to spend time in an active flow cytometry laboratory which performs such tests to develop a procedure manual, quality control procedures and gating approaches which are difficult to create de novo. Again, we sincerely apologize for our initial response. Michael R. Loken, Ph.D. Denise A. Wells, M.D.
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