A new study finds that as HIV progresses it causes exhaustion
of immune system cells. Thus the ability of these cells to combat the virus is
For many years now, scientists have debated whether this
exhaustion of CD8+ T cells is the cause, or the consequence, of persistence of
the HIV virus.
In a study published this week in PLoS Medicine, Marcus
Altfeld and colleagues studied the immune response over time amongst 18
individuals who had very recently become infected with HIV.
These researchers found that the presence of high amounts of
HIV in the blood seemed to cause CD8+ T cell exhaustion; when antigen was
reduced, either as a result of treatment with antiretroviral drugs, or
evolution of viral epitopes to avoid recognition by CD8+ T cells, these
epitope-specific CD8+ T cells recovered some of their original functions.
These findings suggest that CD8+ T cell exhaustion is
the consequence, rather than the cause, of persistent replication of HIV.