APR 16, 2016 05:50 PM PDT

White Blood Cell Types and Functions


White blood cells (leukocytes) are immune system cells that protect the body against diseases and foreign invaders. While they vary in size, they are generally the largest cell type found in the blood. White blood cells reside throughout the body, including in the lymphatic system and in the blood. They make up less than 1 percent of total blood volume. The lifespan of a white blood cell varies from 18 hours to many years.

All white blood cells have nuclei, which makes them different from other blood cells. The five main types of blood cells are basophils, neutrophils, eosinophils, monocytes, and lymphocytes.

Basophils are the cells mainly responsible for allergic reactions. They defend against parasites and bacteria by excreting two chemicals: heparin and histamine. Heparin is a blood-thinning substance. Histamine widens blood vessels and increases blood flow to infected tissues. Basophils are not antigen specific. This means they don't have to determine the identity of the invading substance before taking action against it.

Neutrophils mainly target bacteria and fungus. They are the most abundant type of white blood cell in most mammals. They usually respond and multiply quickly. Neutrophils are formed from stem cells in bone marrow.

Eosinophils target larger parasites, such as worms, and modulate allergic inflammatory responses. For most individuals, eosinophils make up about 1 to 6 percent of all white blood cells.

Monocytes are the largest type of white cell. There are at least three types of monocytes in human blood and they differentiate into macrophages, dendritic cells, and foam cells. Monocytes are produced by bone marrow and circulate in the bloodstream for about one to three days prior to moving into tissues throughout the body. They make up about 3 to 8 percent of white cells.

Lymphocytes work the front lines to identify and destroy foreign invaders. They are the main type of cell found in lymph, the fluid that circulates through the lymphatic system. There are three primary types of lymphocytes: B cells, T cells, and natural killer cells. B cells make up 10 percent of the lymphocytes. They circulate in the front lines of our blood and work to identify foreign invaders. T cells make up 75 percent of lymphocytes. They mature in the thiamin, which is a part of the lymph system, and then migrate to the point of invasion. T cells surround, bind, and help kill foreign invaders. Natural killer cells function to defend against tumors and viruses.
About the Author
  • Julianne (@JuliChiaet) covers health and medicine for LabRoots. Her work has been published in The Daily Beast, Scientific American, and MailOnline. While primarily a science journalist, she has also covered culture and Japanese organized crime. She is the New York Board Representative for the Asian American Journalists Association (AAJA). • To read more of her writing, or to send her a message, go to Jchiaet.com
You May Also Like
NOV 12, 2018
Plants & Animals
NOV 12, 2018
Steaks Aren't the Only Things We Get From Cows
It’s no secret that cows are routinely slaughtered for beef, but what if we told you that only about 60% of the cow gets harvested for food? Fret not...
NOV 14, 2018
Videos
NOV 14, 2018
The Sunscreen Gene
Wouldn't it be convenient if we didn't have to worry about sunscreen because our bodies were able to just make it when we needed it?...
NOV 14, 2018
Plants & Animals
NOV 14, 2018
Here's What Happens When a Fly Lands on Your Food
If you’re like me, then you probably hate it when flies land on your food. But why is it such a big deal anyway? When flies land on your food, it&rsq...
NOV 15, 2018
Cardiology
NOV 15, 2018
An Updated Look At Pacemakers
As pacemakers are now used for a wide range of heart conditions, most of us know someone who has this life-saving medical device. Hundreds of thousands of...
DEC 05, 2018
Cancer
DEC 05, 2018
Zika virus as a weapon against brain cancer
Glioblastoma is the most aggressive type of Brain Cancer with an average survival rate of less than two years with treatment. So what if there could be a cure for this type of cancer....
DEC 12, 2018
Cardiology
DEC 12, 2018
Chest Discomfort May Not Stem From The Heart
Many people who experience symptoms like difficulty breathing, fatigue and tightness in the chest during physical activity, assume the problem stems from t...
Loading Comments...