Lecture 14 - Immune System of Microbio Flashcards by Dasha Gubarev

state of protection against foreign pathogens or substances (antigens)

immunity

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immunis

exempt

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scabs from small pox pustules were used to immunize healthy people

variolation

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Can we generate immunity without inducing disease?

yes through vaccination

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prepares the immune system to eradicate an infectious agent before it causes disease

vaccination

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pathogens fall into four major categories

viruses
fungi
parasites
bacteria

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3 components of the immune system

lymphatic system
primary and secondary lymphoid organs
cells of the immune system

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Production of blood cells

hematopoiesis

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Begins early in embryonic development in the yolk sac
Taken over by the liver and lymphatic organs
Assumed permanently by the bone marrow

hematopoiesis

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2 types of primary lymphoid tissue

bone marrow

thymus

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primary lymphoid tissue is where—

initially develop

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3 types of secondary lymphoid tissue

spleen
lymph nodes
peyers patches in small intestines

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All Blood Cells Arise from the

bone marrow

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site of t cell maturation

the thymus

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Initiated in Secondary Lymphoid Tissues

adaptive immunity

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a surface protection composed of anatomical and physiological barriers that keep microbes from penetrating sterile body compartments

first line of defense

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a cellular and chemical system that comes immediately into play if infectious agents make it past the surface defenses

second line of defense

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includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells

third line of defense

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innate/nonspecific

first and second line

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acquired/specific

third line

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physical barriers, chemical barriers, genetic components

first line

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phagocytosis, inflammation, fever, antimicrobial proteins

second line

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b cells, t cells and their effects

third line

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a first line of defense

barriers

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- Provides microbial antagonism - Blocks access of pathogens to epithelial surfaces - Creates unfavorable environments for pathogens - -----Competes for nutrients - -----Alters local pH

resident microbiota

immunity that we are born with

innate immune system

- stored in the bone marrow and are released when needed to fight infection

neutrophils

Mechanisms of Phagocytic Recognition, Engulfment, and Killing

Four classic signs and symptoms of the inflammatory response:

rubor calor tumor dolor

redness caused by increased circulation and vasodilation in injured tissues

rubor

warmth from the increased flow of blood

calor

swelling from increased fluid escaping from tissues

tumor

pain caused by the stimulation of nerve endings

dolor

fifth sign of inflammation

loss of function

- To mobilize and attract immune components to the site of injury - To set in motion mechanisms to repair tissue damage and localize and clear away harmful substances - Destroy microbes and block their further invasion

inflammation

antibodies

b cells

t cell receptor

t cell

adaptive immune response?

rapid response fixed limited number of specificities constant during response

innate immunity

slow response variable numerous highly selective specificities improve during response

adaptive immuity

Two Arms of the Adaptive Immune Response

humoral and cellular immune response

antibody mediated and b cells

humoral immune response

t cell mediated

cellular immune response

- do not destroy pathogens - binds to pathogens - molecular adaptors

antibiotics

prevent pathogens from binding and inhibit their replication

neutralizing antibodies

Antibodies bind to pathogens and cause their`

Inactivation or Destruction

are the Diverse Receptors of Adaptive Immunity

immunoglobulin and t cells

initially the ab response focuses on ----. next is to focus on ----.

speed, quality.

improved binding by the V regions

somatic hypermutation

improved effector function by the constant regions

isotope switching

Occurs upon first exposure to antigen There is a 3 to 5 day lag period Maximum IgM production in about 7 days Maximum IgG levels after 15 days

primary immune response

distinct properties and traits that enable it to do so

AB isotope

has same 4 phases as primary response

secondary response

differences in secondary compared to primary

time - shorter lag phase, longer plateau, more gradual decline type of antibody - IgG predominant AB titer - higher titer, plateau 10 fold higher

Faster, stronger, better than before More rapid response – lag time is shorter Last longer Larger amount of IgG is generated Ab’s produced have more affinity for the antigen

secondary

an adaptive immune response mediated by specific cells of the immune system

cell mediated immunity

primarily t cells, but also macrophages and NK cells

cell mediated immunity

immunity that can be transferred from one organism to another by lymphoid cells, but not by serum antibodies

cell mediated immunity

involved the destruction of antigen bearing cells by T cells

cell mediated

involved in the use of AB made by b cells

humoral immunity

major effectors of cellular immunity

t cells

comparison of humoral and cell mediated immunity

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Th1 Th2 Provide “help” to B-cells in the form of cytokines to help B-cell proliferation and antibody production Only recognizes Ag with MHC Class II

CD4+ helper T-cells

Responsible for killing virally infected cells | Only recognizes Ag with MHC Class I

CD8+ cytotoxic T-cells

Role of MHC-II proteins - --Found only on Ag-presenting cells (dendritic cells) - -- Display only foreign (exogenous antigen) - --Stimulate the activation of helper (CD4+) T cells

Th cell recognition

MHC-1 proteins - -- Found on nearly all nucleated cells - -- Display peptides produced by host cells or within host cells e.g.: viral infection

Tc cell recognition

Binding of cytotoxic CD8+ cell to abnormal peptides on MHC-1 | Co-stimulation via cytokines

Tc cell activation

is represented by more than one genetic locus

each class of MHC

HLA?

human leukocyte antigen

HLA-A, -B, -C

MHC-I loci

HLA-DR, -DQ -DP

MHC-II loci

Comparison of Class I and Class II MHC Pathways

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Dysfunctions of immunity―two broad categories

1. overly active/misdirected immune response | 2. immunodeficiency

Allergies/asthma Autoimmune disease (e.g., multiple sclerosis, Crohn’s disease)

overly active/misdirected immune response

- Primary (genetic) loss of immune function - Secondary (acquired) loss of immune function - Opportunistic infections (e.g., oral thrush) can occur in people with impaired immune responses

immuodeficiency

where is majority of commensal bacteria

the colon

can kill commensal bacteria

antibiotics

gain a foothold and produce toxins that cause mucosal injury

pathogenic bacteria

leak into gut between injured epithelial cells

red and white blood cells