Phagocyte defects: CGD, LAD, Chédiak–Higashi !

Topic

When neutrophils cannot reach, swallow or kill germs, deep abscesses and fungal infections appear, often with little pus.

Updated 2026-11-01

Key points

CGD: NADPH oxidase defect, no oxidative burst; most often X-linked (CYBB). Infections by catalase-positive germs: S. aureus, Aspergillus, Serratia, Nocardia, Burkholderia cepacia; granulomas.
CGD screening: abnormal dihydrorhodamine (DHR) flow cytometry test; the older nitroblue tetrazolium (NBT) test stays colorless.
LAD type 1: CD18 (β2 integrin) defect, autosomal recessive; delayed umbilical cord separation, omphalitis, infections without pus, very high neutrophil count, periodontitis.
Chédiak–Higashi: LYST gene, autosomal recessive; giant granules in leukocytes, partial albinism, recurrent pyogenic infections, neuropathy, bleeding and a lymphoproliferative accelerated phase.
Isolated low neutrophils (neutropenia) also cause bacterial and fungal infections: the cell count is the first test.

What it is

Neutrophils and macrophages must leave the blood, engulf microbes and kill them with an oxidative burst and granule enzymes. Each step can fail: adhesion (LAD), killing (CGD), or granule formation (Chédiak–Higashi). The result is recurrent bacterial and fungal infections of skin, lungs, lymph nodes and liver.

Phagocyte defects: the table to know

Disease	Defect (gene, inheritance)	What fails	Infections and clues	Key test
Chronic granulomatous disease (CGD)	NADPH oxidase subunits: CYBB X-linked (most common); CYBA, NCF1, NCF2, NCF4 autosomal recessive	Oxidative burst (superoxide) to kill engulfed microbes	Pneumonia, liver and lymph node abscesses, osteomyelitis by S. aureus, Aspergillus, Serratia, Nocardia, Burkholderia; granulomas in gut and bladder	DHR flow cytometry: no rise in fluorescence; NBT test negative
Leukocyte adhesion deficiency type 1 (LAD1)	ITGB2 (CD18, β2 integrin); autosomal recessive	Adhesion and exit of leukocytes from vessels	Cord falls after 3 weeks, omphalitis, skin and mucosal infections without pus, poor wound healing, severe gingivitis	Marked neutrophilia; low CD18 on leukocytes by flow cytometry
Chédiak–Higashi syndrome	LYST (lysosomal trafficking); autosomal recessive	Phagolysosome fusion and granule function; NK cell killing	Recurrent pyogenic infections (S. aureus, streptococci), partial albinism, peripheral neuropathy, easy bleeding, accelerated phase (HLH-like)	Giant granules in neutrophils on the blood smear
Myeloperoxidase deficiency	MPO; autosomal recessive; relatively common	Production of hypochlorite inside the phagolysosome	Usually no symptoms; Candida infections, especially with diabetes	MPO stain of neutrophils

Markers

NADPH oxidase
DHR test
NBT test
CD18
LYST
MPO

Clinical notes

Patients with CGD need avoidance of mulch, hay and decaying leaves, which can cause fungal pneumonia from Aspergillus spores.
In CGD, catalase-negative germs (such as streptococci) are usually not a problem because they release hydrogen peroxide that the neutrophil can still use.
Stem cell transplant can cure CGD, LAD and Chédiak–Higashi syndrome.

Test yourself

Think of the answer, then tap the question to see it.

Why are patients with chronic granulomatous disease prone to catalase-positive organisms?

Catalase destroys the germ's own hydrogen peroxide, so the neutrophil, which lacks NADPH oxidase, has no peroxide left to make killing radicals.

Which test screens for chronic granulomatous disease today?

The dihydrorhodamine (DHR) flow cytometry test, which shows no oxidative burst.

A newborn's umbilical cord has not fallen at 4 weeks, with omphalitis and a very high neutrophil count. What is suspected?

Leukocyte adhesion deficiency type 1 (CD18 integrin defect).

What does the blood smear show in Chédiak–Higashi syndrome?

Giant cytoplasmic granules in neutrophils and other leukocytes.

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Microorganisms

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Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given.

Sources: Chronic granulomatous disease (MedlinePlus Genetics, U.S. National Library of Medicine, 2026); Leukocyte adhesion deficiency type 1 (MedlinePlus Genetics, U.S. National Library of Medicine, 2026); Chediak-Higashi syndrome (MedlinePlus Genetics, U.S. National Library of Medicine, 2026).

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