20.2.4  Lymph nodes

If you look back at Figure 20.3, you can see that lymphocytes accumulate in sites located throughout the body, including the lymph nodes (or lymph glands). When an infection occurs, cells of the immune system, particularly lymphocytes, divide and produce more cells that help fight the infection. This process results in the lymph nodes becoming enlarged, as a result of the increased number of lymphocytes they contain. The lymph nodes in the neck can sometimes be seen as small swellings under the skin, or felt by touching with your fingers, if you have a bad cold or a throat infection. Enlarged lymph nodes may also be felt in the armpits and groin during some other infections. They return to their normal size once the infection has been eliminated.

20.2.3  Lymphocytes and the immune response to infection

20.3  How does HIV disable the immune system?