There are a number of different cell types in circulation in the blood stream. Here's a quick review:
- Red cells carry oxygen to the cells of the body. They are essentially bags of hemoglobin, the oxygen carrying molecule. Hemoglobin binds oxygen to iron atoms, which give the hemoglobin and thus the cells their distinctive red color.
- White cells (leukocytes, "clear cells") are divided into two types:
- Polymorphonuclear cells, are of three types: neutrophils, eosinophils, and basophils.
- Neutrophils fight bacterial infection. They form pus and are the chief ingredient of an abscess. See band cells.
- Eosinophils are cells which are strongly related to allergy and the recognition of foreign things in the body such as parasites.
- Basophils are cells that are also part of the allergy and parasite recognition system.
- Lymphocytes are the virus killers. There are two types of these:
- T-cells which remember what germs we've been exposed to and how to kill them. T-cells are the key component of the immune system that is missing in AIDS.
- B-cells that secrete the actual antibodies that attach to viruses and bacteria and identify them as things to be destroyed - rather like tagging the target with a laser so that the smart bomb will home in and blast the target.
- Monocytes are cells that are related to lymphocytes but have a killing and cleaning function. They cruise through the tissues of the body cleaning up debris and killing any bacteria they find. They are often increased in viral infections - a reassuring finding that your doctor may note on your child's blood count. See mononucleosis.
- Platelets are the cells that plug leaks in the vascular system, the clotting cells.