White blood cells (WBCs)

White blood cells (WBCs), also known as leukocytes, are a part of the body’s immune system. They help protect the body against infections, fight off pathogens like bacteria and viruses, and play a role in inflammation and allergic reactions. Unlike red blood cells (RBCs), which carry oxygen, white blood cells primarily defend the body against disease.

Where are white blood cells normally found?

White blood cells are normally found in the bloodstream and lymphatic system, including the lymph nodes. They circulate throughout the body, patrolling for signs of infection or injury. WBCs can move out of the blood vessels into tissues where needed, such as areas of infection or inflammation. They are produced in the bone marrow and are present in various tissues, including the spleen, lymph nodes, and tonsils.

What are the types of white blood cells and what do they do?

There are several types of white blood cells, each with a specific role in the immune response:

• Neutrophils: These are the most common type of white blood cell. Neutrophils are the body’s first line of defense against bacterial infections. They quickly respond to signs of infection and help destroy bacteria by engulfing them (a process called phagocytosis).
• Lymphocytes: Lymphocytes are key players in the immune system and include two main types:
  • B cells: B cells produce antibodies, proteins that recognize and neutralize foreign substances like bacteria and viruses.
  • T cells: T cells help regulate the immune response and directly attack infected or cancerous cells.
• Monocytes: These cells circulate in the blood and move into tissues, where they become macrophages and histiocytes. These cells are responsible for engulfing and digesting pathogens, dead cells, and other debris.
• Eosinophils: Eosinophils are involved in allergic reactions and help fight parasitic infections. They are also involved in the body’s response to certain types of allergic diseases, such as asthma.
• Basophils: Basophils are the least common type of white blood cell. Basophils play a role in allergic responses and help control inflammation by releasing chemicals like histamine.

What types of cancers are made up of white blood cells?

Cancers originating from white blood cells are called hematologic or blood cancers. Some of the most common types include:

• Leukemia: Leukemia is a cancer of the blood and bone marrow that produces large numbers of abnormal white blood cells. There are several types of leukemia, including acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).
• Lymphoma: Lymphoma is a type of cancer that begins in the immune system, frequently in lymph nodes. The two main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma. Both types involve abnormal growth of lymphocytes.
• Multiple myeloma: Multiple myeloma is a cancer of plasma cells, a type of B cell that produces antibodies. In multiple myeloma, cancerous plasma cells accumulate in the bone marrow and interfere with the production of normal blood cells.

Depending on the specific type and stage of the disease, these cancers can vary widely in their symptoms, treatment, and prognosis.