what does the immune system do
The immune system protects the body against illness and infection caused by bacteria, viruses, fungi or parasites. It is really a collection of reactions and responses that the body makes to damaged cells or infection.he bone marrow makes blood cells that help to fight infection. Weakening of the immune system happens most often in leukaemia or lymphoma. But it can happen with other cancers too. The cancer in the bone marrow stops the bone marrow making so many blood cells.