Innate and adaptive immunity

flashcards for slides on innate and adaptive immunity. wip for now as im just getting these notes down. happy studying!

Lines of defense against invasion

Innate and adaptive

Innate immunity involves

Nonspecific response, using physical barriers and inflammatory response

Physical barriers to invasion

Skin and mucous membranes

Adaptive immunity is…

Specific

Immunity is..

The body’s ability to defend against specific pathogens and / or foreign substances responsible for the development of disease

Innate Immunity time of response

Immediate (minutes / hours)

Innate Immunity Diversity

Limited to classes or groups of microbes

Innate Immunity Microbe recognition

Nonspecific, limited to general patterns on microbes

Innate Immunity Non-self recognition?

Yes

Response to repeated infection - Innate Immunity

Similar with each exposure

Innate Immunity defense

epithelium (skin, mucous membranes), phagocytes, inflammation, fever

Innate Immunity + cellular components

Phagocytes (monocytes/macrophages, neutrophils), NK cells, Dendritic Cells (DCs)

Innate Immunity molecular components

cytokines, complement proteins, acute-phase proteins, soluble mediators

Adaptive immunity Time of response

Dependent upon exposure (1st is delayed, 2nd is more immediate due to antibodies)

Adaptive immunity diversity

Very large; specific for each unique antigen

Microbe recognition in Adaptive immunity

Specific to individual microbes and antigens (antigen/antibody complexes)

Nonself recognition in Adaptive immunity??

yes

Adaptive immunity’s response to repeated infection

Immunologic memory: more rapid and efficient with subsequent exposure

Adaptive immunity defense

Cell Killing; tagging of antigen by antibody for removal

Adaptive immunity + cellular components

T and B lymphocytes, macrophages, DCs, NK cells

Adaptive immunity Molecular components

Antibodies, cytokines, complement systems

Innate immunity cells are…

immediately available / always in stock

Adaptive immunity cells are…

custom made

Cytokines 1/3

Proteins produced by immune cells (innate and adaptive)

Pleiotropic

Redundant

• pro and anti inflammatory

• Systemic and local functions

Colony stimulating factors

• involved in hematopoiesis

  RBCs WBCs Platelets, DC

Cytokines 2/3

Signaling proteins

Primary Messengers of immune response

Interleukins

• from macrophages + lymphocytes

• regulate innate immunity; enhance adaptive immunity

Interferons

• interfere w viral infections

Cytokines 3/3

Tumor Necrosis factor (TNF-alpha)-α

• secreted by macrophages and T cells

• includes acute-phase response, activates neutrophils and endothelial cells, involved in apoptosis

C-Reactive Protein (CRP)

• Acute Phase response

• biomarker of chronic inflammation

Tumor Necrosis factor (TNF-alpha)-α

secreted by macrophages and T cells

includes acute-phase response, activates neutrophils and endothelial cells, involved in apoptosis

CRP (c-reactive protein)

Acute Phase response

Biomarker of chronic inflammation

TNF-α

Tumor Necrosis factor - alpha

CRP

C-reactive protein

Chemokines

Attracts WBCs to infection (chemo-attractant)

CC, CXC, C, CX3C

Involved in acute and chronic inflammation

Innate immunity mechanisms

Epithelial barriers , phagocytic cells, NK cells (Lymphocytes), PRR

Soluble Mediators: Opsonins, cytokines, acute-phase proteins

Plasma proteins: complement system

Complement system

made up of a large number of distinct plasma proteins that react with one another to opsonize pathogens

PRR

Pathogen recognition response

Innate Immunity: epithelial barriers

Ports of entry: skin, GI, respiratory, urogential tracts

Physical: skin, mucous membranes

Mechanical: mucus, cilia, coughing + sneezing

Biochemical: Enzymes

Enzymes in biochemical barrier

• Lysozymes (tears, saliva, breast milk)

• Defensins (GI tract)

• Complement system (Blood)

Cells of innate immunity

Neutrophil

Macrophage

Dendritic cell

NK Cells

Neutrophil

• First responder

• Phagocyte, enzymes

• 55% of WBC

• Short life span

• migrates from blood into tissues

Macrophage

• Phagocyte, APC

• Used to be a monocyte

• Reside in tissues, long lived

• consumes foreign pathogens and stimulates response of other immune cells

APC

Antigen presenting cell; plays a role in adaptive immunity

Dendritic cells

• presents in epithelial tissue - skin lung digestive tract

• migrates to lymph nodes upon activation

• APC*

NK cells..

directly kill infected cells (ie tumor or virus infected)

circulates in blood and migrates from the tissues

Features of NK cells

• 2 receptors: Activating and inhibitory

• NK cell checks cells’ ID: MHC I self-recognition peptide

Process of NK checking cell ID

• When ID checks out, NK cell moves to next cell

• If no MHC I or MHC I self-recognition peptide doesn’t match - cell directly killed by NK cell

Opsonins

Marks microorganisms for immune response

ie Acute-phase proteins, lectins, complement proteins

Inflammatory cytokines

circulate the blood at all times

orchestrates immune response (both innate and adaptive)

Ex. TNFα, IL-1, IL-6, IL-12, interferons, chemokines

Acute phase proteins are…

Produced in the liver, enhance immune response, released during inflammation. Enhances binding of phagocytes, activates complement pathway

• ie Mannose-binding leptin (MBL), C-reactive protein (CRP)

Complement proteins are ..

A powerful effector of immune response as they’re highly toxic proteins that destroy microorganisms once activated. Considered an effector for Innate and Humoral immunity

List the 3 main pathways for the complement proteins:

Classical

Lectin

Alternative

classical pathway involves

Adaptive (humoral) Immunity and antibodies

Alternative complement system involves the….

innate immune response (no antibodies)

The lectin complement system..

activates lectin pathway when lectin binds to mannose (no antibodies, so innate immune response)

Mannose

sugar monomer. Important in human metabolism, especially in the glycosylation (adding carbs to protein = glycoprotein) of certain proteins.

What is the complement system?

an early-step inflammatory response in the body

involves 9 complement proteins (C1-C9)

All three pathways lead to…

activation of C3, which turns into C3a and C3b

Complement protein C5b is involved with..

Late-step membrane attack (Mac attack)

Mac attack

C5b initiates attack

C5b + C6 - C9 complex drills hole, allows fluids and ions to enter cell, causes lysis of microbe

Adaptive immunity is the..

final line of defense for the body

What activates adaptive immunity

innate system initiating inflammation

(Adaptive Immunity) Repeated exposure leads to…

Increased immune response

Humoral Immunity

• B cells that produce antibodies

• Extracellular microbes and toxins

Cell-Mediated Immunity

• T cells

• Intracellular microbes (viruses)

antigens are…

Substances present on surface of pathogens that elicit an adaptive immune response

Antigens come in the form of..

Proteins, Polysaccharides, lipids, nucleic acids

A spike protein is..

Antigen that causes adaptive immune response

Epitopes are..

• Immunologically active sites on antigens

• Smaller part of antigen recognized by immune cell receptors or antibodies

Cells and Molecules of Adaptive immunity

Lymphocytes - B and T lymphocytes

Lymphocytes features

• Specificity: Each clone of T and B cells is specific to one epitope on an antigen (flu vaccine)

• Diversity

• Memory (life long or short term) - Think Chicken pox vs Covid 19 vaccine

• Self/non-self recognition

B Lymphocytes

Produce antibodies

mediate humoral immunity

T lymphocytes

Cell-mediated immunity

several types of t cells

B cells mature in the…

bone marrow

B cells can…

• Develop immunoglobulins (antibodies)

• Learn to distinguish self from non-self

T cells mature in the…

thymus

What is Thymic selection

where t cells can..

• Distinguish self from non-self

• Recognize different antigens (diversity)

• 100% pass rate required

Move to lymph nodes to await activation

Regulatory cells…

preplan and control the immune response

ie t helper and suppressor cells, antigen presenting cells (Macrophages and dendritic cells)

Effector cells…

carry out attacks on antigens

ie killer t cells, b cells → plasma cells → antibodies, leukocytes

T Lymphocytes can…

• Activate T and B cells

• Control intracellular viral infections

• Activate delayed Type IV hypersensitivity reactions- Poison ivy

• Activate autoimmune processes

T lymphocytes are involved in the..

Rejection of foreign tissue grafts

CD (cluster of differentiation) molecules

• CD4+ (helper T cells)

• CD8+ (cytotoxic T cells)

• CD25+ (regulatory T cells)

T cells can be identified by..

Cell surface molecules

Helper T cells..

are the master regulators for the immune system

can release cytokines to direct function of other cells

Helper t cells can differentiate to..

• T1H cells: which stimulate phagocytes and B cells

• T2H cells: which stimulate B cells, eosinophils, mucosal epithelial cells, and the inflammatory response

Helper T cells can be…

CD4+ cells become activated by antigens on MHC-II molecules on antigen-presenting cells

Regulatory T cells

TREGS = CD25+, CD4+

• Suppress immune responses by inhibiting proliferation of other lymphocytes

Dependent on following conditions:

• Presence of antigen

• Activation of T-cell receptor by antigen

• Release of cytokines

Cytotoxic T cells

Monitor every cell in the body

Recognize antigens on class I MHC molecules and destroy infected cells

Cytotoxic T cells destroys target cells by…

• Cytotoxic enzymes

• Trigger apoptosis – programmed cell death

• Cytokine release

B lymphocytes

• Provide humoral immunity

• Eliminate extracellular microbes and toxins

• Create memory for heightened and rapid response with future exposure

B lymphocytes and humoral immunity

T helper cells signal B cell transformation

→ Plasma cells secrete antibodies

→ Memory B cells hang around waiting for the next exposure to the antigen

Antibodies / Immunoglobulins

• Y-shaped proteins produced by plasma cells

• Released into blood and lymph

• Find microorganisms

• Form antigen-antibody complex

• Bind to and destroys antigens

IgG desc.

Largest, all body fluids, binding antigens (most prevalent)

IgA desc.

Found in blood, secretions, and on mucous membranes; breast milk → newborn protection

IgM

Circulates in body fluids; has five units to clump antigens together. Prominent in early humoral immune response; produced by fetus

IgD

B cell receptor

IgE

Found on mast cells and basophils; involved in inflammation and the allergic response (hay fever).

Primary immune response

Antigen presented on MHC-II

• T helper cells activate

• B-cell proliferation and differentiation

• Plasma cells produce antibodies

• Memory B cells ready and waiting for secondary response

Plasma antibody levels rise

Takes 1 - 2 weeks

Secondary Immune response

• Second or subsequent exposure to antigens

• Memory B cells respond to the antigen immediately

• Plasma antibody levels rise within days

Vaccination…

produces a primary immune response.

• Plasma cells

• Memory cells

Booster shots….

cause a secondary immune response

• Immediate rise in antibody levels

MHC – Major Histocompatibility Complex Molecules

Cell surface proteins that help immune system distinguish self from nonself (self-recognition peptides)

• Ex. native molecules vs foreign molecules

3 classes of MHC

I, II, III

Based on function