Mechanism of Pathogen Killing by Innate Immune Cells

What cells are phagocytes

Macrophage, neutrophil, DC

What is M1

Classical macrophage

What is M2

Alternatively activated macrophage

What is the function of M1

Killing of bacteria and fungi

What is the function of M2

Killing of helminth

What activates M1

IFN gamma and TLR ligands

What activates M2

IL4, IL13

What are the mechanisms of phagocytosis

Chemotaxis, adherence, ingestion, killing/degradation

What are the killing mechanism in phagolysosomes

ROS, RNS and enzymes

What does ROS do

NADPH oxidase generates supraoxide that leads to oxidative burst

What does RNS do

iNOS produces NO that is toxic to pathogen

What enzymes are in the phagolysosome

Lysozyme, protease and defensin

What is the function of phagolysosome enzymes

Break down pathogen cell wall

Which leukocytes have granules

Neutrophils, NKs, cytotoxic T cell

What is the function of AMP on innate immune cells

Activate innate immune cells to produce cytokine, activate adaptive immunity cells by presenting pathogen to CD8

What is the antibacterial mechanism of AMP

Interfere with DNA/RNA formation and protein folding, destroy cell wall

What is the function of defensin and cathelicidin

insert into microbe membrane to cause lysis

What is the function of lysozyme

Break down peptidoglycan in call wall

What is the function of lactoferrin

Bind to iron to starve bacteria

What are systemic protective effects

Fever by brain, acute phase protein production in liver, leukocyte production in bone marrow

What cytokines induce fever and leukocyte production

TNF, IL1, IL6

What induces acute phase protein production

IL1 and IL6

What are local inflammation processes

Increased WBC migration to infection, WBC recruitment

What are the acute inflammation response

Vasodilation and vascular leakage, fever and hyperalgesia, leukocyte recruitment, release of acute phase protein

What is NET

DNA of neutrophil that traps pathogen

What is netosis

Death of neutrophil due to NET

Too much NET can cause what

Inflammatory response or RBC occlusion

What does NK cell produce during first response

IFN beta, TNF alpha and IL12

What does NK cell do during secondary response

Kill infected cell

What activates NK cell

Recognition of infected/damaged or tumor cells

How does normal cell inhibit NK cell

Normal cell has self MHC class I bound to inhibitory receptor of NK cell