ib202 immune system- chapter A

Innate Immunity

-inherent in all animals and cells ready to respond to foreign invaders at all times

-rapid and generic response

Adaptive Immunity

-occurs in only vertebrates

-cells are first selectively activated to tailor response to specific pathogen

-slow response

-memory

3 Key processes of Innate Immunity

1) preventing entrance of potential pathogens

2) detects presence of pathogen by distinguishing from animal’s own body

3) eliminates pathogen

Preventative Barriers of Pathogens

-insects covered with cuticle (exoskeleton)

-soft-bodied invertebrates AND VERTEBRATES Covered w/ protective mucus layer

-human skin has dead cell layer

Outer Surface Layers: Human Skin

-oil secreted by skin cells and converted to fatty acids by bacteria which lower pH and prevent growth of pathogens

Lysozyme

-protects body

-waxy secretion in ears

-antibiotic in tears

-breaks the bacterial cell wall

How are Openings in the Body Protected?

-lysozyme

-mucus

-cilia

-hair

2 things that can detect pathogens?

-TLR (toll-like receptors) and cytokines

TLRs

-toll-like receptors

-on macrophages and dendritic cells, T cells, B cells, and non-immune cells

-induce release of cytokines

How was TLR discovered? Flies

-fungal infection in flies was more severe when lacking toll protein

How was TLR discovered? Mice and Humans

-identified by exposing them to antigens which act as receptors to receive signal that pathogen is present

Leukocytes, Response and Characteristics

-white blood cells

-provide immediate, generic response against broad group of pathogens (except lymphocytes)

-alerted to presence of invaders by antigens found on pathogen surface

-phagocytic

Neutrophils

-most abundant type of leukocyte

-phagocytic

-recruited by cytokines and move to sites of infection/inflammation

Macrophages and Cytokines

-macrophages activated by contact w pathogen

-danger signals release cytokines

Cytokines

-small secreted proteins released by cells and have effect on interactions and communication between cells

What are cytokines produced by?

macrophages, lymphocytes

Role of cytokines

-adaptive immunity like activation, differentiation, and proliferation

--recruit immune cells to fight pathogens

Effect of too many cytokines

-excess inflammation and autoimmune diseases

Mast Cells and histamine

-mast cells release histamine to bloodstream (allergic response) when allergen is triggered

Histamine Functions

-histamine is inflammatory mediator and promotes vascular and tissue change

-histamine increases permeability of capillaries to WBCs and protein to engage pathogens in infected tissue

Dendritic Cells Location

-leukocytes: phagocytic cells

-present in tissues w/ contact to external environment

Activated Dendritic Cells

-migrate to lymph nodes, interact with T and B cells to initiate and shape adaptive immune response

Inflammation

-response to harmful stimuli: pathogens, damaged cells, irritants

-involves immune cells, blood vessels, and molecular mediators

-generic response

Function of Inflammation

1) eliminate initial cause of injury

2) clear dead cells and tissues dmgd from OG insult and inflammatory process

3) initiate tissue repair

TLRs and SARS COV 2

-innate immune system activated through TLR signaling

-TLRs can induce transcription of pro-inflammatory cytokines

Cytokine Storm

-induction of immune signaling by TLRs leads to pro-inflammatory cytokines at high rates

-causes acute respiratory distress syndrome (ARDS)

-positive feedback of inflammatory cytokines on other immune cells causing organ damage