BIOG251 Chapter 12.2: Innate Immune System

The defenses that make up the innate immune system…

The first and second line of defense

Second line of defense

General defenses that support and interact with immune responses

Viral PAMPs

Double stranded RNA

Bacterial PAMPs

Peptidoglycan and the LPS

Fever

High body temperature due to infection

The _______ line of defense is very general in action

First

Phagocytes, dendritic cells, endothelial cells, and lymphocytes

Where PRRs are found in the host

Neutrophils, Monocytes, and Macrophages

The types of phagocytes

The steps of phagocytosis

Chemotaxis → adhesion → engulfment and phagosome formation → phagolysosome formation → destruction → elimination

Phagosome

Packet containing a pathogen resulting from phagocytosis

Phagolysosome

Lysosome fused with a phagosome

Why are phagolysosomes necessary?

Lysosomes provide the required enzymes for destruction and elimination

Elimination

Waste/debris is released from the destruction of the pathogen

How do phagocytes adhere to the pathogen?

The PRR on the phagocyte binds to the PAMP on the pathogen

Inflammasome

Use PRRs to identify PAMPs and start the inflammatory response

Membrane Attack Complex (MAC)

Made up of C5b, C6, C7, C8, used to attack the pathogen’s cell membrane

Complement Cascade initiation

C3 protein binds to a pathogen and splits into C3a and C3b

Complement Cascade activation and cascade

C3b cleaves C5 into C5a and C5b

Complement Cascade polymerization

C5b forms the MAC with C6, C7, and C8

Complement Cascade membrane attack

MAC attacks the pathogen’s cell membrane by creating pores, eventually leading to lysis

Interferons

Signaling proteins that communicate when there is infection and increase antiviral proteins