White blood cells macro

White blood cells, or leukocytes, are immune system cells that defend the body against infections and diseases.

About this subject

Leukocytes are produced in the bone marrow and circulate through blood and lymphatic system. There are five main types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specific functions. Neutrophils, the most abundant, attack bacteria and fungi. Lymphocytes include B and T cells, responsible for adaptive immunity. Monocytes transform into macrophages that phagocytize pathogens. Eosinophils combat parasites and are involved in allergies. Basophils release histamine in allergic reactions.

The normal white blood cell count in blood ranges from 4,000 to 11,000 cells per microliter. Elevated counts may indicate infection, inflammation, or leukemia, while low counts can be caused by medications or autoimmune diseases. The discovery of white blood cells dates back to the 17th century when Antonie van Leeuwenhoek observed them under a microscope. Today, differential analysis of these cells is crucial for clinical diagnoses.

Bright-field microscopy with Romanowsky stains (such as Giemsa or Wright) allows visualization of nuclei and cytoplasmic granules, facilitating identification of cell types. In pathological conditions, morphological changes like a left shift (increase in immature neutrophils) signal acute bacterial infection. Ongoing research in immunology explores how leukocytes recognize antigens, form immunological memory, and contribute to cancer therapies, such as CAR-T cell immunotherapy.

Frequently Asked Questions

What is considered a high white blood cell count?

A count above 11,000 cells per microliter is generally considered high (leukocytosis), which may indicate infection, inflammation, or leukemia.

What are the functions of T and B lymphocytes?

T lymphocytes attack infected cells and regulate immune response, while B lymphocytes produce antibodies against specific antigens.

How is white blood cell count measured?

The count is done via a complete blood count, which analyzes a blood sample using automated analyzers or manual microscopy.