Concerning the article by de Carvalho Bittencourt et al.: Value of HIV patients with regular follow‐up as in‐house internal controls of flow cytometry measurement of lymphocyte subsets

The Brief Communication by de Carvalho Bittencourt et al. [10.1002/cyto.b.21112] was originally reviewed by three anonymous reviewers. One of the two outside reviewers thought that the suggestion of a robust in-house control did not make sense as a validation approach and recommended rejection. The second reviewer had significant reservations but suggested several changes. A request was made to revise the paper. A second figure demonstrating the variations in absolute CD4 counts was added (Fig. 2). On re-examination, this second reviewer felt that their previous suggestions were not fully implemented. Overall, there was the notion that patient samples are being recommended as robust in-house controls in place of traditional or conventional controls for validation. The authors responded noting that “this type of in house and patient-base validation indeed provides a good and regular quality control in a field where external QC is scarce and often different from actual patient samples, as stated in the guidelines, although they obviously cannot replace such controls.” In further discussion, it was noted that although many of the patients did indeed have reasonably consistent or stable data, there would be exceptions. It was noted that patient compliance with therapy would have to be part of such a QC process. It was finally decided that a short report might be warranted but it should be accompanied with appropriate commentary before advocating such an approach to other laboratories. Toward that end, the following two opposing commentaries have been provided. The first commentary is from Dr. Frank Mandy who was for many years in charge of the QC/QA program for Health Canada. Dr. Mandy also had experience with CD4 T-cell counting in the developing world. With financing provided by the U.C.L.A. Fogarty Institute, Dr. Mandy ran Quality Assessment and Standardization for Immunological measures relevant to HIV/AIDS (QASI) from Canada, an external quality management program without cost to participants. QASI included approximately 500–600 laboratories from 50 countries, mostly from Africa, the Americas, and Asia. Dr. Mandy’s commentary begins. “The authors go back to the classic dilemma surrounding management of quality control and quality assessment strategy differences confronting scientists in clinical chemistry versus immunophenotyping of leukocyte subsets in infectious immunology. The authors do not dissect the two types of daily internal quality assessment that the operator must conduct. First, demonstrate that the instrument is performing within acceptable limits and next, validate specimen processing and reagent stability. The authors suggest that the daily immunophenotyping processing assessment can be eliminated without compromising repeatability and reproducibility of test results. This position is supported by accumulative data from 32 HIV-infected individuals over a period exceeding a decade based on CD3/CD4/ CD8 values and previously published information by Bender (1992) and O’ Gorman (2008) regarding antiretroviral therapy (ART) efficacy monitoring. This unorthodox approach to use the robustness of the immunophenotyping data of HIV-infected individuals under treatment is open to criticism. The authors base their conclusion on accumulative results of individuals on ART to serve as longitudinal in-house process control over 12 years with variable follow-up frequency from 7 to 63. To convince quality laboratory managers, a much larger study is required where the noncompliant individuals and drug resistance cases are confirmed independently from CD4 T-cell counts and are removed from the data. The remarkable consistency of CD4 T-cell counts over long time is open to suspicion. Patients were probably preselected, as getting the common cold will cause dramatic drop in CD4 T-cell count, smoking or exercises can also have significant impact. In addition, over a decade, many individuals must have had change in ART cocktail composition, which usually has impact on CD4 T-cell levels. There is a fundamental distinction between specimens analyzed for immune status assessment and monitoring assay performance. Addressing such disregard to conventional quality management approach will require more rigorous support to substantiate credibility. The role of external quality assessment was ignored. However, the author’s data suggest some promise and it should be considered as a valuable technical observation.