CD4 T cell measurements in the management of antiretroviral therapy--A review with an emphasis on pediatric HIV-infected patients.

The measurement of both the percentage (in pediatric patients aged less than 5 or 6 years) and the absolute number of circulating CD4+ T cells remains the single most important parameter for establishing prognosis and determining when to treat HIV-1 infected infants. The predictive power of CD4+ T cell measurements in HIV-1 infected individuals has resulted in robust guidelines from numerous agencies on the use of CD4+ T cell measurements ranging from pretreatment evaluations to the initial assessment and monitoring of therapeutic responses and treatment failures. The increase in availability of HIV-1 antiretroviral drugs in resource limited setting has led to the urgent need to develop systems and technologies for the accurate and cost-effective measurement of CD4+ T cells. The establishment of standardized guidelines for antiretroviral therapy (including CD4 testing) along with significant advancements in the development of structured access to health care, centralized CD4 testing programs, improved quality assurance programs, and inexpensive CD4 measurement technologies are making CD4 testing more universally available. Recent evidence suggests that a CD4/CD8 ratio of less than 1 may provide a reliable marker of presumptive HIV-1 infection in HIV-1 exposed infants. This review will summarize the current guidelines for the use of CD4 testing in HIV-1 infected infants and the potential for the CD4:CD8 ratio to be used as a surrogate of HIV-1 infection in resource limited settings. Copyright 2008 Clinical Cytometry Society.