External quality assessment program on CD4+ T-lymphocyte counts for persons with HIV/AIDS in Thailand: History and accomplishments

Faculty of Public Health, Mahidol University, Bangkok, Thailand.
Asian Pacific journal of allergy and immunology / launched by the Allergy and Immunology Society of Thailand (Impact Factor: 0.97). 12/2009; 27(4):225-32.
Source: PubMed


A CD4 count External Quality Assessment (EQA) program is important for the clinical monitoring of persons infected with HIV/AIDS. The purpose of the present study was to evaluate the CD4 EQA performance program of the flow cytometer laboratories that perform routine CD4 counts for these patients in Thailand. Stabilized whole blood samples were sent to participating laboratories to determine the percentage and absolute counts of CD4+ T-lymphocytes using their routine procedures. The data were analyzed and reports sent to the participants within one month. Most participating laboratories produced results that were within two standard deviations (SD) of the mean, while the average inter-laboratory coefficients of variation were less than 8% for CD4+ T-lymphocytes. This program was found to improve the reliability of CD4+ T-lymphocyte determinations. This test is becoming increasingly important as Thailand and other Southeast Asian countries scale up their national programs that provide access to antiretroviral therapy for persons living with HIV/AIDS.

Download full-text


Available from: Vallerut Pobkeeree,
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: CD4 T-lymphocytes play a vital role in maintaining the integrity of the human immune system. They are also the primary target cells for human immunodeficiency virus (HIV). The progressive depletion of these cells eventually results in weakening of the host's immune ability to fight against any pathogen, thus rendering the host susceptible to infections and leading ultimately to death of patients in the terminal stage of acquired immune deficiency syndrome (AIDS). Although several clinical and laboratory parameters have been used for monitoring disease progression and the effectiveness of HIV antiretroviral therapy (ART), it is the simple measurement of CD4+ T-lymphocytes that remains the single and most important parameter for management of HIV-infected patients in resource-limited settings. To date, flow cytometer is considered to be the most accepted technology for both percentage and absolute CD4+ T-lymphocyte determination because of its accuracy, precision and reproducibility. However, flow cytometer based CD4 testing is relatively expensive, complex and thus technically demanding. Simple innovative approaches applicable to the conventional flow cytometric system and new technologies have been successfully developed to increase cost saving especially for use in resource-challenged settings. Principles of the existing dual- and single-platform approaches as well as several affordable CD4 measurement technologies are discussed along with both internal and external quality control systems in the management of laboratories performing CD4 testing.
    Asian Pacific journal of allergy and immunology / launched by the Allergy and Immunology Society of Thailand 03/2012; 30(1):11-25. · 0.97 Impact Factor