Revista de SIDA e investigación clínica

The Total Lymphocyte Count is a Factor When Using the CD4 Count to Guide HIV Therapy

Abstract

Peter Hansen, Dorothy Sylvia, Michelle DeLelys and Frederic Preffer

Therapy initiation at confirmation of HIV-infection is now medically preferred, which implies that, with adequate financial support, the diagnostic use of T-helper lymphocyte parameters will shift from ART enrollment to tracking therapeutic response. Of the two main therapy tracking parameters, CD4% and the CD4 count, the CD4% parameter is less prone to non-HIV influences. For example, normal CD4% values do not change at all during 17 years of healthy childhood maturation while the CD4 count falls by approximately a factor of three. In mature, HIV-stable persons the CD4 count randomly fluctuates by approximately 12% from day to day in health and by 30% in severe HIV-infection; while CD4% fluctuates by one-third of these amounts respectively. Despite indications such as these that CD4% is the best cell proxy for HIV-related immune status, CD4% is not delineated in adult therapy guidelines and not universally measured by smaller commercial cytometers in resource challenged areas. With only the CD4 count available how might one determine whether a result was subject to factors that would call for a repeat count at a later time? We showed in two populations (African and American) that the normality of the total lymphocyte count was an indicator of the utility of a given CD4 count. High or low lymphocyte counts were strongly related to a high or low CD4 count, which means that factors such as stress and microbial infection that are known to temporarily affect the total lymphocyte count will affect the CD4 count. During HIV therapy the total lymphocyte count should be inclined to normal values and a lymphocyte count that is high or low relative to a patient’s history would call for a repeat CD4 measurement at a later time and, more importantly, qualify the repeat measurement.