To review recent progress in the development and evaluation of rapid CD4 cell assays needed to treat HIV-infected individuals in resource-poor countries.

Field tests indicate that many simplified flow-based assays provide CD4 cell numbers comparable to the current standard, FACSCount, at a lower cost. Most are intended for use at centralized clinics, but some new assays are portable. The manual assays, Dynal T4 Quant and cyto-spheres, are useful when only a few tests are performed daily. Several new formats include a manual rosetting method that uses a unique anti-CD4 cell monoclonal antibody that does not bind to monocytes. Microchip digital imaging and immunochromatography assays are being developed with the goal of being less expensive, more portable and easier than current methods. Reagents that increase the stability of blood samples and clinical reagents in tropical climates are being field tested.

The availability of antiretroviral medications increases the need for CD4 cell assays to monitor disease progression and the efficacy of therapy in resource-poor countries. Simplified flow cytometry is needed in centralized clinics, but there is a critical need for even less expensive easier methodology that can be used in smaller laboratories and in rural villages.