rganautaWhite blood cells in 3D
White blood cells, or leukocytes, defend the body against infections and foreign substances. Unlike red blood cells and platelets, they all have a…
Explained for every age
For kids (7–11)
White blood cells are your body's defense team. There are five kinds, and each one has its own job: some eat germs, others make special weapons and others raise the alarm. They are all born inside your bones, in the bone marrow.
For teens (12–16)
White blood cells, or leukocytes, defend the body against infections and foreign substances. Unlike red blood cells and platelets, they all have a nucleus. There are five classic types: neutrophils, lymphocytes, monocytes, eosinophils and basophils, from most to least abundant. They are divided into granulocytes, with tiny granules visible inside and a lobed nucleus (neutrophils, eosinophils and basophils), and agranulocytes, with a round or kidney-shaped nucleus (lymphocytes and monocytes). They all form in the bone marrow; T lymphocytes finish maturing in the thymus.
Pre-Med (17+)
Leukocytes: nucleated cells derived from multipotent hematopoietic stem cells in the bone marrow, found in blood, lymph and tissues. Normal adult count ≈ 4,000–11,000/µL (≈ 1% of blood volume). Morphological classification: polymorphonuclear granulocytes (neutrophils, eosinophils, basophils) versus mononuclear agranulocytes (lymphocytes, monocytes); classification by lineage: myeloid (neutrophils, eosinophils, basophils, monocytes) versus lymphoid (T, B and NK lymphocytes). Approximate proportions: neutrophils ≈ 50–70%, lymphocytes ≈ 20–40%, monocytes ≈ 2–10%, eosinophils ≈ 1–4% and basophils < 1% (mnemonic: “Never Let Monkeys Eat Bananas”). B lymphocytes mature in the bone marrow and T lymphocytes in the thymus. Leukocytosis: a rise above the upper limit, common in infection and inflammation and less often neoplastic (leukemias); leukopenia: a fall, often due to fewer neutrophils (neutropenia).
What you can explore
EosinophilBasophilNatural killer cellRegulatory T cellMemory T cellThymic T-cell selectionMHC antigen presentationHIV and CD4 T cells
Missions
- The defense team Explorer
- Reading a blood count Discoverer
- Cellular immunology Pre-Med