People with HIV and their physicians could have a less
expensive tool to track the progression from HIV infection
to AIDS. According to researchers from the Johns Hopkins
Bloomberg School of Public
Health, a decline in the total lymphocyte counts, or
TLC, and hemoglobin concentration in the blood may be used
to monitor a patient's disease status.
Currently, HIV RNA and CD4+ cells in the blood are
measured, but specialized equipment and training for lab
technicians makes these measurements expensive. TLC and
hemoglobin measurements are much less expensive and can be
obtained by using standard blood tests. The study, "Rapid
declines in total lymphocyte counts and hemoglobin
concentration prior to AIDS among HIV-1-infected men,"
appears in the September issue of AIDS, the journal of the
International AIDS Society.
According to lead author Bryan Lau, a graduate student
in the Department of
Epidemiology, "This study demonstrates that there is a
biological event that occurs during the progression of HIV
infection leading to declines in TLC and hemoglobin within
individuals. The majority of HIV individuals who develop
AIDS experience a rapid decline in total lymphocyte counts
and hemoglobin concentration that starts about one and one
half years prior to developing AIDS," he said. "The decline
in these two markers in individuals who develop AIDS shows
that this is an important event in the pathogenesis of the
The authors analyzed longitudinal measurements of TLC
and hemoglobin in 3,299 homosexual and bisexual men
enrolled in the Multicenter AIDS Cohort Study from 1984
through 1991. The researchers found that for many years
after HIV infection, TLC and hemoglobin markers are stable
and provide little information about HIV disease
progression to AIDS.
However, as HIV disease progresses, TLC and hemoglobin
begin to decline rapidly. A TLC decline greater than 10
percent per year and hemoglobin decline greater than 2.2
percent per year was present in more than 77 percent of the
study participants who developed AIDS and absent from more
than 78 percent of individuals who did not develop AIDS.
To further support their findings, the researchers
explained in their study that current World Health
Organization guidelines suggest the use of TLC measurements
for monitoring an individual's HIV infection in developing
countries if CD4+ cell counts are not known. Hemoglobin
levels also have been shown to have an association with
progression from asymptomatic HIV infection to AIDS.
Currently, in order to begin antiretroviral therapy
for asymptomatic HIV-infected individuals, measurements of
HIV RNA levels and CD4+ lymphocyte counts in the blood are
required. These measurements are expensive and require
technological expertise and equipment that is typically not
available in developing countries.
Contributing author Joseph Margolick, a professor in
the Department of Molecular Microbiology and Immunology,
said, "These results could be very useful for regions with
scarce heath care resources as an alternative way of
identifying individuals who should receive drug therapy for
HIV infection. We believe further research in appropriate
populations is warranted."
Stephen J. Gange, an adjunct associate professor in
the Department of Epidemiology, was also a co-author of the
The Multicenter AIDS Cohort Study is funded by the
National Institute of Allergy and Infectious Diseases and
the National Cancer Institute.