Bio 328 Immunology

Phagocytosis and Intracellular killing

PHAGOCYTOSIS.

Professional phagocytes:

- Neutrophils (PMN, microphages)

- Monocytes/macrophages (mononuclear phagocytes).

Neutrophil

Monocyte

Niels Borregaard (1997)

PHAGOCYTOSIS.

Chemotaxis:

- Chemoattractants:

fMLP chemokines

anaphylatoxins

PAF, Leukotriene B4

- Extravasation.

Rolling, adhesion, diapedesis, migration.

PHAGOCYTOSIS.

- Recognition (opsonization)

- Ingestion

- Killing

phagolysosome fusion

O2 burst

- Digestion

Innate, active host defenses

Soluble defenses

Cellular defenses

Initiation adaptive immune

response

http://www.youtube.com/watch?v=fpOxgAU5fFQ

Brown GD (2006) Dectin-1: a signalling non-TLR pattern-recognition receptorNat Rev Immu 6: 33–43 doi:10.1038/nri1745

Methods of pathogen recognition by pattern-recognition receptors (PRRs).

Griffin FM, Griffin JA, Leider JE and Silverstein SC (1975) J. Exp. Med. Figure 3.

Griffin FM, Griffin JA, Leider JE and Silverstein SC (1975) J. Exp. Med. Figure 3.

PHAGOCYTOSIS.

Oxygen burst: increased

- consumption of oxygen

- consumption of glucose

- production of superoxide anion, hydrogen peroxide, hydroxyl anion

- production of CO2

- production of lactic acid

- production of bleach

Results: Bone marrow derived murine neutrophil Respiratory burst

Eric Campbell, 2010.

Increased consumption

Increased production

OxygenGlucose

LactateCO2

ROPBleach

NADPH+H+

NADP+

Glucose

6 CO2 MPO

Lysosome

O2

O2- H2O2

Pathogen

Oxygen burstneutrophils

OxidaseHMS

gp91p22

Cytb558

gp91

p22gp91 p22

Rac-2

GTP

Rac-2

GTPp67

p67

P67NOXA

p47

p47

P47NOXO

P

P

Rac-2

GDP

+PNADP+NADPH+H+

GEF

O2 O2-

MembraneHeme

HemeHeme

NOX-Organizer

NOX-Activator

Nitric oxide synthase

Possible oxidant-generating reactions of stimulated PMNs

Monoxygenase IReduction of one O2,

one O in hydroxyarginine,one O in water

Monoxygenase IIReduction of one O2

one O in NO,one O in water

2x 4 electrons required to reduce 2 O2 are derived from: NH3 NO (5 electrons) and

1.5 NADPH+H+ 1.5 NADP+ (3 electrons)

L-arginine + O2 + NADPH+H+ NO + L-citruline + NADP+

Ribbon diagram of human defensin. Numbers indicate the position of the cysteine residues; disulphide bonds are shown in yellow.

The defensin dimer is stabilized by multiple hydrogen bonds and hydrophobic interactions at the monomer-monomer interface. The top of the dimer is polar; the base is apolar.

Rat peritoneal neutrophils, which often contain ringed nuclei are stained (antibody) for the presence of defensins. Defensins (blue) are present in the cytoplasm and have a granular distribution.

Neutrophil extracellular traps: an additional antibacterial weapon.

Nature Reviews Immunology 9, 364-375 (May 2009)

Shigella flexneri entrapped by NETs.

Shigella flexneri entrapped by NETs.

Pseudomonas aeruginosa entrapped by mast cell extracellular traps.

Pseudomonas aeruginosa entrapped by mast cell extracellular traps.

PHAGOCYTOSIS.

Deficiencies:

- Chronic Granulomatous Disease

- G6PD-deficiencies

- Chediak-Higashi syndrome

- Leukocyte adhesion deficiency

- Neutrophil specific granule Deficiency

- Myeloperoxidase deficiency

Results: CGD mouse bone marrow neutrophil Respiratory burst

(Eric Campbell, 2010)

Chediak Higashi Syndrome: defect in LYST, lysosomal trafficking regulator

Leukocyte adhesion defect type 1 presenting with recurrent pyoderma gangrenosum

Father and daughter with autosomal dominant (AD) hyperimmunoglobulin E syndrome (HIES). Note the father's distinctive facies with prominent forehead, deep-set eyes, broad nasal bridge, and wide interalar distance.

Mother and son with autosomal dominant (AD) hyperimmunoglobulin E syndrome (HIES). Note the mother's distinctive facies. She had a history of multiple deep-seated abscesses that took months to heal after incision and drainage.

Hyperimmunoglobulin E or Job’s Syndrome: Defect in IL-17 secretion.

The End