However, even though the cells appear normal, they do not function as normal cells. Monocytes are the second type of white blood cell. They are also important in defending the body against pathogens. The lymphocytes form the third type of white blood cell. They have different functions within the immune system.
Antibodies are proteins that can attach to the surfaces of bacteria and viruses.
This attachment sends signals to many other cell types to come and destroy the antibody-coated organism. The T cell protects the body against viruses. When a virus enters a cell, it produces certain proteins that are projected onto the surface of the infected cell. In addition, the T cells can destroy some types of cancer cells. Chronic leukemias develop very gradually.