Elevated
CD8 Cell Count Predicts HIV Treatment Failure
SUMMARY
High or rising CD8 T-cell counts after starting combination
antiretroviral therapy appears to predict virological
treatment failure. |
By
Liz Highleyman
CD4
"helper" T-cells are the primary target of HIV and
CD4 cell count is a key measure of immune system health and
response to antiretroviral
therapy. But CD8 "killer" T-cells also play
a role in immune response against HIV and give important information
about disease progression.
As
described in the May
11, 2011, advance online edition of the Journal of Acquired
Immune Deficiency Syndromes, Elizabeth Krantz from
the Uniformed Services University of the Health Sciences and
colleagues evaluated whether elevated CD8 cell counts are
associated with increased risk of virological treatment failure
in people with HIV.
This retrospective cohort study included 817 HIV positive
participants in the U.S. Military HIV Natural History Study,
comprised of service members, veterans, and their families,
who started highly active antiretroviral therapy (HAART) between
1996 and 2008. About half started during 1996-1999, soon after
the advent of effective combination therapy using protease
inhibitors.
Participants had undetectable HIV RNA (below 400 copies/mL)
at 6 and 12 months after starting treatment. They also had
at least 2 subsequent viral load tests and available baseline
CD8 count information. The median follow-up period was about
4 years.
Results
 |
The
overall median CD8 count fell by 61 cells/mm3 during the
first year on HAART. |
|
12%
of participants experienced a total of 216 treatment failures
(defined as confirmed HIV RNA >400 copies/mL),
for a rate of 5.6 per 100 person-years. |
|
Virological
failure was more common among people who started HAART
during the early part of the study period, before 2000. |
|
Among
participants who initiated HAART during 2000-2008, patients
with elevated baseline CD8 cell counts (defined as >
1200 cells/mm3) had significantly greater risk of virological
failure than those with baseline CD8 counts <
600 cells/mm3 (hazard ratio 2.68, or nearly 3 times higher
risk). |
|
Participants
with elevated CD8 counts at more than 20% of prior follow-up
visits had significantly greater risk of treatment failure
at the current visit than those who did not (hazard ratio
1.53). |
|
People
whose CD8 cell counts increased after starting HAART had
significantly greater risk of virological failure than
those with decreasing or stable CD8 counts. |
|
People
who experienced treatment failure had a median increase
of 51 CD8 cells/mm3, while those who maintained undetectable
viral load had a median decrease of 108 CD8 cells/mm3.
|
Based
on these findings, the study authors concluded, "Initial
or serial elevated CD8 counts while on HAART or an increase
in CD8 counts from HAART initiation may be early warnings
for future treatment failure."
Investigator affiliations: Infectious Disease Clinical
Research Program, Uniformed Services University of the Health
Sciences, Bethesda, MD; Division of Biostatistics, University
of Minnesota, Minneapolis, MN; San Antonio Military Medical
Center, Fort Sam Houston, TX; Walter Reed Army Medical Center,
Washington, DC; Naval Medical Center San Diego, San Diego,
CA; National Naval Medical Center, Bethesda, MD; Tripler Army
Medical Center, Honolulu, HI; 8 Naval Health Research Center,
San Diego, CA.
6/21/11
Reference
EM
Krantz, KH Hullsiek, JF Okulicz, et al. Elevated CD8 counts
during HAART are associated with HIV virologic treatment failure.
Journal of Acquired Immune Deficiency Syndromes (abstract).
May 11, 2011 (Epub ahead of print).
