Figure 1.

Memory CD4 T-cells in anti-HIV immunity. (A) Naïve CD4 T-cells are derived from CD4 lineage progenitors. Upon meeting a pathogen, such as HIV, naïve CD4 T-cells differentiate into antigen specific effector cells. Some of them die due to the viral infection or their biological destinies, whereas some of them survive and become memory cells and further develop into secondary effector cells. These memory cells retain the stem cell properties of asymmetric division, self-renewal, and differentiation into effector cells. (B) When encountering HIV again, these antigen specific memory T-cells, in this case HIV specific, repeat the process in (A), and majority of effector cells die but some of memory cells sustain to continue the cycle. In general, the earlier the application of HAART is, the more memory cells preserve or survive. (C) The memory CD4 T-cells act as a commander in chief, in the leadership position for launching anti-HIV immunity as these cells govern functions of both CD8-cells and B-cells, regulate both cellular and humoral immunities, by which determine the prognosis of AIDS.