8 Types of White Blood Cells

01
of 08

8 Types of White Blood Cells

Macrophage and Bacteria
These Mycobacterium tuberculosis bacteria (purple) are infecting a macrophage white blood cell. The macrophage, when activated, will engulf the bacteria and destroy them as part of the body's immune response. Credit: Science Photo Library/Science Photo Library/Getty Images

8 Types of White Blood Cells

White blood cells are the defender's of the body. Also called leukocytes, these blood components protect against infectious agents (bacteria and viruses), cancerous cells, and foreign matter. White blood cells develop from stem cells in bone marrow. They circulate in blood and lymph fluid and may also be found in body tissues.

Macrophages

Monocytes are the largest of the white blood cells. Macrophages are monocytes that are present in nearly all tissue. Macrophages digest cells and pathogens by engulfing them in a process called phagocytosis. Lysosomes within the macrophages release hydrolytic enzymes which destroy the pathogen. Macrophages also aid in adaptive immunity by presenting information about foreign antigens to immune cells called lymphocytes. Macrophages perform a number of functions outside of immunity. They assist in sex cell development, steroid hormone production, resorption of bone tissue, and blood vessel network development.

  • Dendritic Cells
  • B Cells
  • T Cells
  • Natural Killer Cells
  • Neutrophils
  • Eosinophils
  • Basophils

 

02
of 08

Dendritic Cells

Dendritic Cell
Artistic rendering of the surface of a human dendritic cell illustrating the unexpected discovery of sheet-like processes that fold back onto the membrane surface. Credit: National Cancer Institute (NCI)/Sriram Subramaniam/Public Domain

Dendritic Cells

Like macrophages, dendritic cells are monocytes. Dendritic cells have projections that extend from the body of the cell that are similar in appearance to the dendrites of neurons. They are commonly found in tissues located in areas that come in contact with the external environment, such as the skin, nose, lungs, and gastrointestinal tract. Dendritic cells help to identify pathogens by presenting information about these antigens to lymphocytes in lymph nodes and lymph organs.

  • Macrophages
  • B Cells
  • T Cells
  • Natural Killer Cells
  • Neutrophils
  • Eosinophils
  • Basophils

03
of 08

B Cells

B cell Lymphocyte
B cells are a type of white blood cell involved in immune response. They account for 10 percent of the body's lymphocytes. Credit: Science Photo Library - STEVE GSCHMEISSNER/Brand X Pictures/Getty Images

B Cells

B cells are a class of white blood cell called a lymphocyte. B cells produce specialized proteins called antibodies to counter pathogens. Antibodies help to identify pathogens by binding to them and targeting them for destruction by other immune system cells. B cells known as memory B cells help to protect against future infections from previously encountered germs by retaining information about the germ's molecular signature. This provides long-term immunity against specific pathogens.

  • Macrophages
  • Dendritic Cells
  • T Cells
  • Natural Killer Cells
  • Neutrophils
  • Eosinophils
  • Basophils

04
of 08

T Cells

Cytotoxic T Cell
This cytotoxic T cell lymphocyte kills cells infected with viruses, or are otherwise damaged or dysfunctional, through release of cytotoxins perforin and granulysin, which cause lysis of the target cell. Credit: ScienceFoto.DE ­ Oliver Anlauf/Oxford Scientific/Getty Images

T Cells

Like B cells, T cells are also lymphocytes. T cells are produced in bone marrow and travel to the thymus where they mature. T cells actively destroy infected cells and signal other immune cells to participate in the immune response. T cell types include cytotoxic T cells, helper T cells, regulatory T cells, natural Killer T (NKT) cells, and memory T cells. Cytotoxic T cells directly terminate infected cells, helper T cells help B cells produce antibodies, and regulatory T cells suppress the response of B cells and other T cells to antigens. NKT cells have properties of both T cells and another type of lymphocyte known as a natural killer cell. NKT cells are T cells and not natural killer cells.

  • Macrophages
  • Dendritic Cells
  • B Cells
  • Natural Killer Cells
  • Neutrophils
  • Eosinophils
  • Basophils

05
of 08

Natural Killer Cells

Natural Killer Cell Granule
This electron micrograph image shows a lytic granule (yellow) within the actin network (blue) at the immune synapse of a natural killer cell. Credit: Gregory Rak and Jordan Orange, Children's Hospital of Philadelphia

Natural Killer Cells

Natural killer (NK) cells are lymphocytes that circulate in the blood in search of infected or diseased cells. Natural killer cells contain granules with chemicals inside. When NK cells come across a tumor cell or a cell that is infected with a virus, they surround and destroy the diseased cell by releasing the chemical containing granules. These chemicals break-down the cell membrane of the diseased cell initiating apoptosis and ultimately causing the cell to burst. Natural killer cells should not be confused with certain T cells known as natural Killer T (NKT) cells.

  • Macrophages
  • Dendritic Cells
  • B Cells
  • T Cells
  • Neutrophils
  • Eosinophils
  • Basophils

06
of 08

Neutrophils

Neutrophil Cell
Stylized image of a neutrophil, one of the white blood cells of the immune system. Credit: Science Picture Co/Getty Images

Neutrophils

Neutrophils are white blood cells that are classified as granulocytes. They are phagocytic and have chemical containing granules that destroy pathogens. Neutrophils possess a single nucleus that appears to have multiple lobes. These cells are the most abundant granulocyte in blood circulation. Neutrophils quickly reach sites of infection or injury.

  • Macrophages
  • Dendritic Cells
  • B Cells
  • T Cells
  • Natural Killer Cells
  • Eosinophils
  • Basophils

07
of 08

Eosinophils

Eosinophil Cell
Stylized image of an eosinophil, one of the white blood cells of the immune system. Credit: Science Picture Co/Getty Images

Eosinophils

Eosinophils are phagocytic white blood cells that become increasingly active during parasitic infections and allergic reactions. Eosinophils are granulocytes that contain large granules, which release chemicals that destroy pathogens. Eosinophils are often found in connective tissues of the stomach and intestines. The eosinophil nucleus is double lobed and often appears U-shaped in blood smears.

  • Macrophages
  • Dendritic Cells
  • B Cells
  • T Cells
  • Natural Killer Cells
  • Neutrophils
  • Basophils

08
of 08

Basophils

Basophil Cell
Stylized image of a basophil, one of the white blood cells of the immune system. Credit: Science Picture Co/Getty Images

Basophils

Basophils are granulocytes (granule containing leukocytes) whose granules contain substances such as histamine and heparin. Heparin thins blood and inhibits blood clot formation. Histamine dilates blood vessels and increases blood flow, which helps the flow of white blood cells to infected areas. Basophils are responsible for the body's allergic response. These cells have a multi-lobed nucleus and are the least numerous of the white blood cells.

  • Macrophages
  • Dendritic Cells
  • B Cells
  • T Cells
  • Natural Killer Cells
  • Neutrophils
  • Eosinophils