HIV's prime cellular victim can itself kill affected cells during the early days of infection. And it seems that the more vigorous this response by CD4 T cells is, the greater an HIV-positive person's chance is of being able to maintain a relatively low viral level and the better their disease outcome is likely to be.

Hendrik Streeck at the Ragon Institute in Charlestown, Massachusetts, and his colleagues studied two groups of people with untreated HIV during the first year of infection. By the end of the period, members of one group had developed a higher viral load than had those of the other. The authors found that patients with a lower HIV load had a greater percentage of HIV-specific CD4 T cells. Moreover, at the beginning of the study, a higher proportion of CD4 T cells in these patients expressed proteins, particularly one called granzyme A, that kill other cells.

The authors say that measuring the responses of these T cells during the early stages of infection could allow medics to predict how HIV infection will progress in individual patients.

Sci. Transl. Med. 4, 123ra25 (2012)