What is a basophil?

Basophils:

- Least common of the circulating WBCs.

- Derived from the myeloid stem cells.

- Represent 0.5-1.0% of circulating WBCs.

- Appear in the peripheral blood as fully differentiated end cells.

- Increased numbers (>2%) are seen in some allergic conditions & certain other inflammatory diseases, such as ulcerative colitis.

- Increased numbers of blood basophils are seen after exercise, adrenalin injection or emotional stress.

- Have abundant dark blue, almost black, cytoplasmic granules containing histamine, serotonin, chondroitin sulfate, heparin and other mediators of inflammation.

- Function: Involved in allergic reactions, defense against parasites and in other inflammatory reactions in the body.

Morphology:

- Size 8-12 µm.

- Oval or kidney-shaped nucleus with deep notches.

- Abundant basophilic cytoplasmic granules.

- Poorly granulated basophils are also found in some cases of leukemia. These are called atypical basophils.