Lecture 24- Innate Immunity, phagocytosis and non specific cell mediated responses

Properties and Roles of the Adaptive Defenses

1) not a general defense

2) happens in response to specific, pathogen, often directed against individual strains

3) response is slower

4) response is long lasting (memory)

Adaptive Immunity Cells

1) activation of T cells, T helpers stimulating cytotoxic T lymphocytes (CTLs) to kill infected host cells and stimulate B cells to make antibodies

2) activation of B cells, antibody producing 8 lymphocytes that release specific antibodies against a pathogen

Properties of Second Lines of Defenses

1) happen if first line defense are compromised

2) many cell mediated defense

3) heavily interdependant, interwoven

Goal of Second Line of Defense

pathogen clearance, pathogen presentation to adaptive immune system

6 Stages of Phagocytosis

1) chemotaxis

2) adhesion

3) ingestion

4) maturation,

5) killng

6) elimination

Body’s Second Line of Innate Defense, post invasion

operated when pathogens penetrate the skin or mucous membranes, composed of cells antimicrobial chemicals, designed to clear pathogens, many originate in blood

3 Major Functions of Second Line of Innate Defense

phagocytosis, complement, or inflammation

Players in the Body’s Second Lines of Defense

stem cells, can make more of themselves and turn into many different types of cells

Hematopoiesis

process where blood stem cells differentiate (turn into) all blood cell types to have cell mediated innate immune functions

6 Cells from the Blood Stem Cells

1) platelets, clotting formation

2) basophils, inflammation

3) neutrophils, phagocytosis

4) eosinophils, inflammation

5) monocyte, macrophages, phagocytosis

6) lymphocytes, lymphoid stem cell

6 Stages of Phagocytosis

1) chemotaxis0 moving to the site of invasion, by complement chemokines

2) adhesion, binding to the invader

3) ingestion, engulfing the invader (bacteria, yeast, viruses, dead cells), forming the phagosome (intracellular enclosed space), opsonization

4) maturation, preparing the invader for destruction, forming phagolysosome

5) killing, destroying the invader, phagolysosome releases lysozyme, proteases, defensins, HCl, nitric oxide, degrades bacteria

6) elimination, removing the invader’s debris, release of bacterial fragments and antigen presentation

Pathogen Clearance by Phagocytes

neutrophils, monocyte/macrophages, dendritic cells

Opsonization

when a molecule enhances phagocytosis by marking the target for engulfment

C3b and IgG/IgM

enhance opsonization by 1000 fold

Neutrophils Movement

from bone marrow through bloodstream to site of infections induced by complement components like chemoattractant

Cytokines

inflammatory molecules at site on infection activage neutrophils

Complement System, 4 Steps

1) cytokines stimulate transmigration of neutrophil

2) C5a guides neutrophils to area where microbe is growing

3) cytokines activate neutrophils

4) C3b coats microbes, aids neutrophil to ingest them

How Does the Innate Immune SYstem recognize Pathogens?

PAMPs, interferon complement, evolved to recognize and respond to pathogens that have gotten through first line of defense (self vs non self)

PAMPs

pathogen associated molecular patters, associated with groups of microbes that are recognized by cells of innate immune system

5 Types of PAMPs

1) LPS

2) flagellin

3) peptidoglycan

4) lipoproteins/ lipids

5) dsRNA

PRRs

pattern recognition receptors, recognizes PAMPS in plants and animals

2 Different PRRs

1) toll like receptors (TLRs)

2) NOD Like receptors (NLRs)

Mechanism of Action of Human Alpha and Beta Interferons

1) virus infects cell

2) viral components trigger activation of type I IFN genes

3) tater the infected cell may dies, releasing various

4) binding activates genes for antiviral proteins

5) same neighboring cilia at the later times

6) if this cell is infected, viral components activate ethe APs

7) activate AVPs degrade mRNA and watch stops protein synthesis, preventomg socal media jobs