HIV transmitted through sexual activity
enters the bloodstream via mucous membranes lining the
vagina, rectum and mouth. Macrophages and dendritic cells on the surface of mucous
membranes bind virus and shuttle it into the lymph nodes, which
contain high concentrations of helper T cells (CD4+ T cells).
Once HIV has entered the body, the immune system initiates anti-HIV antibody and cytotoxic T cell
production. However, it can take one to six months for an individual
exposed to HIV to produce measurable quantities of antibody. The immune response is weakened as memory T cells (CD4+ CCR5+) are destroyed.
The figure shows a scanning EM picture of a dendritic cell interacting with helper T cells. This process occurs in lymph nodes and regulates immune responses.
Copyright ©1999 Massachusetts Medical Society. All rights reserved. Used and adapted with permission.
New England Journal of Medicine 340:1732