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Hana Mariah binti Saim

10-1-303 (Section 9)

Defects in Leukocyte Function

Defects in leukocyte function, both genetic and acquired, lead to increased vulnerability to

infections:

1. Defects in leukocyte adhesion

2. Defects in phagolysosome function.

One such disorder is, Chédiak-Higashi syndrome an autosomal recessive condition characterized by

neutropenia (decreased numbers of neutrophils), defective degranulation, and delayed microbial

killing.

3. Defects in microbicidal activity.

The importance of oxygen-dependent bactericidal mechanisms is shown by the existence of a group

of congenital disorders with defects in bacterial killing called chronic granulomatous disease.

Genetic

1.Leukocyte adhesion deficiency 1

Leukocyte adhesion deficiency-1 (LAD-1) is a type of leukocyte

adhesion deficiency attributable to mutations in the gene

on chromosome 21 at position q22.3. Blood neutrophil counts are

usually significantly elevated even when no infection is present

because of an inability of the cells to adhere to vascular endothelium

and migrate out of the intravascular compartment. Those soaffected have histories of delayed separation of theumbilical

cord, omphalitis, gingivitis, recurrent skin infections, repeated otitis

media, pneumonia, septicemia, ileocolitis, peritonitis, perianal abscesses, and impaired wound

healing.

2. Leukocyte adhesion deficiency 2

is a type of leukocyte adhesion deficiency attributable to the

absence of neutrophil sialyl-LewisX, a ligand of P- and E-selectin on

vascular endothelium. similar to those seen in patients with LAD-1,

including pneumonia, peridontitis, otitis media, and localized

cellulitis.

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3. Chronic granulomatous disease

Chronic granulomatous disease is an inherited disorder

in which immune system cells called phagocytes do not

function properly. This leads to ongoing and severe

infection. Impetigo, skin abscesses and furuncles, and

perianal and rectal abscesses are common in people

with this disorder.

4. Chediak-Higashi syndrome

ChédiakHigashi syndrome is a rare autosomal recessive disorder

that arises from a microtubule polymerization defect which leads

to a decrease in phagocytosis. The decrease in phagocytosis

results in recurrent pyogenic infections, partial albinism and

peripheral neuropathy.

Acquired

Chemotaxis: defined as a unidirectional migration of cells towards an injured tissue along a chemical

gradient.

-thermal injury, diabetes, malignancy, sepsis, immunodeficiencies

Adhesion: occurs due to interactions between complementary adhesive

molecules on the leukocytes and on the epithelium.

-Hemodialysis, diabetes mellitus

Phagocytosis and microbicidal activity: is a process which neutrophils

and macrophages engulf the offending pathogen such as bacteria,

dead cells and foreign bodies.

- Leukemia, anemia, sepsis, diabetes, neonates, malnutrition.

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