A Simple Manual Rosetting Method for Absolute CD4 Lymphocyte Counting in Resource-Limited Countries

A CD4 monoclonal antibody which reacts with CD4 lymphocytes but does not react significantly with monocytes was generated and used to develop a simple method for CD4 count. In a comparison with standard flow cytometry, high correlation was obtained. The developed method can be an alternative to flow cytometry for resource-limited countries. The incidence of human immunodeficiency virus (HIV) in-fection and clinical disease continues to increase rapidly in underdeveloped and developing countries (13). As antiretro-viral therapy is becoming more affordable and accessible, the provision of affordable CD4 testing for initiating and monitor-ing antiretroviral therapy has emerged as a vital issue. Flow cytometry, the existing benchmark method for CD4 lympho-cyte enumeration, is expensive and is not affordable for most developing countries. These factors necessitate the need for simple and inexpensive alternative methods for CD4 count. Recently a CD4 monoclonal antibody (MAb), named MT4, was generated in our laboratory (8). When white blood cells (WBC) (n 4) were stained with MAb MT4, for all tested subjects, CD4 lymphocytes showed strongly positive reactivity (Fig. 1B, donors 1 and 2). Monocytes from two out of four tested subjects were negative (Fig. 1B, donor 1), whereas the rest of the tested subjects showed very weak reactivity (Fig. 1B, donor 2). Granulocyte population in all tested subjects wa