White blood cells macro

White blood cells (leukocytes) are immune system cells that defend the body against infections and foreign invaders.

About this subject

White blood cells, also known as leukocytes, are essential components of the immune system. Produced in the bone marrow and present in blood and lymphatic tissues, they defend the body against pathogenic microorganisms such as bacteria, viruses, and fungi, as well as remove dead cells and debris. There are five main types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specialized functions.

Neutrophils are the most abundant, responding rapidly to bacterial and fungal infections through phagocytosis. Lymphocytes include B cells and T cells, responsible for adaptive immunity and immunological memory. Monocytes differentiate into macrophages in tissues, engulfing pathogens and presenting antigens. Eosinophils combat parasites and are involved in allergic reactions. Basophils release histamine in inflammatory responses.

The normal white blood cell count in blood ranges from 4,000 to 11,000 per microliter. Elevated counts (leukocytosis) may indicate infection, inflammation, or leukemia, while low counts (leukopenia) increase susceptibility to infections. Light microscopy with staining (e.g., Wright's stain) allows identification of different cell types based on nucleus shape and cytoplasmic granules.

The discovery of leukocytes dates back to the 19th century with Elie Metchnikoff's work on phagocytosis and Paul Ehrlich's on cell staining. Today, leukocyte analysis is routine in complete blood counts, aiding in the diagnosis of numerous clinical conditions.

Frequently Asked Questions

What are white blood cells?

White blood cells, or leukocytes, are blood cells that are part of the immune system and defend the body against infections, foreign substances, and diseased cells.

What is the function of neutrophils?

Neutrophils are the most common type of leukocyte and primarily defend against bacterial and fungal infections by phagocytizing (engulfing) and destroying invading microorganisms.

What does leukocytosis mean in a blood test?

Leukocytosis is an elevated white blood cell count, usually above 11,000 per microliter. It can indicate infection, inflammation, stress, or leukemia.