If you have leukopenia, your levels of infection-fighting white blood cells, or leukocytes, are too low. Because neutrophils are the most common white blood cell, neutropenia also is used to describe low white cell counts.

The thymus gland is a small gland in your upper chest that has importance for your health far out of proportion to its size. It starts functioning during fetal life, manufacturing millions of immune cells called T cells.

During menses, or menstruation, a female sheds blood during her monthly cycle. This period can be draining for many girls and women, and they do not feel their best.

Smoking weakens the immune system by depressing antibodies and cells that are in the body to protect against foreign invaders.

Many people rely on caffeine to get them up in the morning and sustain them throughout the day. However, high caffeine intake can increase the impact that physical and mental stress has on your body.

Your immune system is a vital part of your overall well being. If it is weak, then you are more susceptible to getting sick and developing serious illnesses. If you were recently sick with a virus, then it is all the more important to get it revved back up to avoid the next virus that comes to town.

Allergies are a common condition that effects nearly everyone at some point in their lives. An allergic response is the result of the immune system's overreaction to an unknown particle or substance. Paint allergies can result from the inhalation of strong vapors or contact with the skin.

Exercise is like a medication. In the correct dose, it can be beneficial, but in excess, it can be harmful. Different athletes have different tolerances for stress. A grueling workout for one person might be a routine workout for another.