Two Phase III studies are now underway to determine the clinical effect, if any, of interleukin-2. If the trials end positively, interleukin-2 will become the first therapy directed specifically at increasing cell number and improving immune function. Increase in cellular activation. As a consequence of HIV infection, the immune system loses CD4 T cells and experiences functional deficits. Paradoxically, it is also in a state of hyperactivation, which results from the chronic nature of HIV infection and unrelenting cycles of viral replication.
Chronic activation damages the immune system further and propagates the infection.
Despite its importance, chronic activation is arguably the component of HIV pathogenesis to which investigators have paid the least attention. In the setting of HIV infection, stimulation of the immune system increases virus production and programmed cell death, both of which in turn accelerate cell loss and diminished cellular responses to antigen, further impairing the immune system's functional competence. These observations are not without clinical consequence. Vaccinations, such as those against pneumococcal pneumonia and influenza, as well as prophylaxis against Pneumocystis pneumonia and Mycobacterium avium complex, are intended to prevent specific clinical diseases. However, by preventing fulminant infections, vaccination precludes episodes of immune activation and may therefore also be important to delaying HIV disease progression.