Two Hypotheses about
Resistance to HIV
Perhaps some people are not infected by HIV because of an unusual, effective immune response against HIV. Such a response would probably be performed by cytotoxic CD8+ cells. We can test this theory by seeing if CD8+ cells from an exposed uninfected person can protect their CD4+ cells from HIV.
We’ll use two types of cells from each person to be tested:

1. CD4+ cells should be infected by HIV.
2. CD8+ cells would perform any immune response that prevented infection of the CD4+ cells.

Each person's CD4+ cells are mixed with HIV, with and without that person's CD8+ cells, and virus production is monitored. From controls like the one on the right, we see that CD4+ cells from most people are infected by HIV, whether CD8+ cells are present (orange circles) or not (red circles).

INSTRUCTIONS:
Click NEXT to view the data from this experiment, performed on five HIV-resistant people.