Evaluation of dynabeads and cytospheres compared with flow cytometry to enumerate CD4+ T cells in HIV-infected ugandans on antiretroviral therapy
Journal of Acquired Immune Deficiency Syndromes
Academic Alliance for AIDS Care and Prevention, Infectious Diseases Institute, Kampala, Uganda; Makerere University, Kampala, Uganda; Division of Infectious Diseases, Johns Hopkins Medical Institutions, Baltimore, MD, United States; University of Manitoba, Winnipeg, Canada; National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States; Division of Infectious Diseases, Johns Hopkins Medical Institutions, 1830 East Monument Street, Baltimore, MD 21287, United States
BACKGROUND: Laboratory-based monitoring of antiretroviral therapy is essential but adds a significant cost to HIV care. The World Health Organization 2006 guidelines support the use of CD4 lymphocyte count (CD4) to define treatment failure in resource-limited settings. METHODS: We compared CD4 obtained on replicate samples from 497 HIV-positive Ugandans (before and during ART) followed for 18 months by 2 manual bead-based assays, Dynabeads (Dynal Biotech), and Cytospheres (Beckman Coulter) with those generated by flow cytometry at the Infectious Diseases Institute in Kampala, Uganda. RESULTS: We tested 1671 samples (123 before ART) with Dynabeads and 1444 samples (91 before ART) with Cytospheres. Mean CD4 was 231 cells/mm (SD, 139) and 239 cells/mm (SD, 140) by Dynabeads and flow cytometry, respectively. Mean CD4 was 186 cells/mm (SD, 101) and 242 cells/mm (SD, 136) by Cytospheres and flow cytometry, respectively. The mean difference in CD4 count by flow cytometry versus Dynabeads were 8.8 cells/mm (SD, 76.0) and versus Cytospheres were 56.8 cells/mm (SD, 85.8). The limits of agreement were -140.9 to 158.4 cells/mm for Dynabeads and -112.2 to 225.8 cells/mm for Cytospheres. Linear regression analysis showed higher correlation between flow cytometry and Dynabeads (r = 0.85, r = 0.73, slope = 0.85, intercept = 28) compared with the correlation between flow cytometry and Cytospheres (r = 0.78, r = 0.60, slope = 0.58, intercept = 45). Area under the receiver operating characteristics curve to predict CD4 <200 cells/mm was 0.928 for Dynabeads and 0.886 for Cytospheres. CONCLUSION: Although Dynabeads and Cytospheres both underestimated CD4 lymphocyte count compared with flow cytometry, in resource-limited settings with low daily throughput, manual bead-based assays may provide a less expensive alternative to flow cytometry. © 2008 Lippincott Williams & Wilkins.
antiretrovirus agent; virus RNA; antiviral therapy; article; blood sampling; CD4 lymphocyte count; CD4+ T lymphocyte; controlled study; female; flow cytometry; human; Human immunodeficiency virus infected patient; Human immunodeficiency virus infection; human tissue; intermethod comparison; laboratory test; male; priority journal; Uganda; virus load; adult; CD4+ T lymphocyte; comparative study; evaluation; flow cytometry; highly active antiretroviral therapy; Human immunodeficiency virus infection; immunology; immunomagnetic separation; methodology; monitoring; Adult; Antiretroviral Therapy, Highly Active; CD4 Lymphocyte Count; CD4-Positive T-Lymphocytes; Female; Flow Cytometry; HIV Infections; Humans; Immunomagnetic Separation; Male; Monitoring, Physiologic; Uganda