White Blood Cells

Neutrophil

A normal neutrophil count is 2.0 - 7.5 * 109. (total WBC 4 - 11)

Neutropaenia refers to a low neutrophil counts, < 1.5 * 109.

It is important to recognise as it predisposes to severe infection.

Neutropaenia may be further subdivided as follows:

Severity	Neutrophil count
Mild	1.0 - 1.5 * 109
Moderate	0.5 - 1.0 * 109
Severe	< 0.5 * 109

Causes

viral
- HIV
- Epstein-Barr virus
- hepatitis
drugs
- cytotoxics
- carbimazole
- clozapine
benign ethnic neutropaenia
- common in people of black African and Afro-Caribbean ethnicity
- requires no treatment
haematological malignancy
- myelodysplastic malignancies
- aplastic anemia
rheumatological conditions
systemic lupus erythematosus: mechanisms include circulating antineutrophil antibodies
rheumatoid arthritis: e.g. hypersplenism as in Felty's syndrome
severe sepsis
haemodialysis

Eosinophils perform the following functions:

Parasitic defense: Eosinophil proliferation and activation during parasitic infection is stimulated by IL-5 produced by T_2 and mast cells. When a parasite invades the mucosa or enters the bloodstream, it is coated by IgG and IgE antibodies that bind the Fc receptors located on the eosinophil cell surface. This triggers eosinophil degranulation and release of cytotoxic proteins (eg, major basic protein) and reactive oxygen intermediates, substances that damage and destroy antibody-bound parasites. This mechanism is an example of antibody-dependent cell-mediated cytotoxicity (ADCC), which is also used by macrophages, neutrophils, and natural killer cells.