ABSTRACT
HIV/AIDS, first recognised in the early 1980s, is now the largest infective cause of death in the world. This virus infects and destroys the CD4+ cells that are at the heart of the body’s adaptive immune system. CD4+ helper T lymphocytes (Th cells) recognise microbial antigens presented to them by antigen-presenting cells (APCs). They also stimulate effector cells, the CD8+ T-cytotoxic lymphocytes (Tc cells) and B cells, which produce antibodies. Both the CD8+ Tc cells and the antibodies are specifically targeted to attack the same antigen recognised by the CD4+ Th cell. Not only this, but the generation of memory Tc and B cells is also stimulated by Th cells. By studying how HIV/AIDS evolves, and how the body responds, we can understand much of the way the immune system works. CD4 receptors are found on cells other than Th cells.
