Chapter 10: Adaptive Immune System

Dengue Fever

Tropical viral disease spread by mosquitoes.

• RNA virus

  • easily mutable

• viral disease

• only female mosquitoes sting for their eggs

• we react to mosquito spit

adaptive immune system pathway

1. Macrophage engulfs the germ (doesn’t kill) 

2. Presents antigen to T cell

   • Helper T can show the antigen to the B-cell 

   • Cytotoxic T-cell can kill other germs 

3. B-cell makes copies of itself and releases antibodies 

4. Antibodies mark the germ for kill 

• pathogen specific; takes longer to develop

Macrophage

Engulfs pathogens and presents antigens

• antigen presenting cell

Antigen

Substance that triggers an immune response.

• foreign

T-Cell

Lymphocyte that attacks infected cells.

• helper T

• cytotoxic T

• responsible for memory cells

B Cell

Lymphocyte that produces antibodies.

• also makes plasma cells which turn into memory cells

• attacks outside the cell

Helper T Cell

Activates B cells and cytotoxic T cells.

• messenger

Cytotoxic T Cell

Kills infected or cancerous cells.

Antibodies

Proteins that bind to specific antigens to indicate to APC to attack

• takes weeks to produce

• Antibodies are in plasma coming from proteins 

• Tips have specific antigen-binding site 

  • T cell is needed

Immunological Memory

Ability to remember past antigens for faster response.

Herd Immunity

Protection of a population through widespread immunity.

Innate Immunity

Natural, immediate immune response to pathogens.

• non-specific

• quick

• epithelial barriers, antimicrobial proteins, phagocytes, dendritic, NK cells

Adaptive Immunity

Specific immune response that develops over time.

• leads to immunological memory

• B and T cell

• takes weeks to develop

  • specific lifelines for viruses vary

Phagocytes

Cells that engulf and digest pathogens.

Dendritic Cells

Antigen-presenting cells that activate T cells.

Natural Killer Cells

Cells that destroy infected or cancerous cells.

Histamine

Chemical released during allergic reactions.

Mast Cells

Cells involved in allergic responses and inflammation.

• hypersensitivity

• secondary bacterial infection

hypersensitivity

body overreaction to an invasion to a foreign particles such as pollen

secondary bacterial infection

immune system encounters an antigen it has previously been exposed to

• symptoms last longer than 10-14

Vaccine

Substance that stimulates immunity against diseases.

Differentiation

Process of stem cells developing into specialized cells.

Opsonization

Making pathogens more susceptible to phagocytosis by coating them in antibodies

MMR Vaccine

Vaccine effective against measles, mumps, rubella.

Memory Cells

Cells that remember past infections for faster response.

Lymphoid Tissue (spleen)

Tissue where immune cells mature and activate.

• lymph nodes

• trillions of antibodies in memory cells that our body keeps track of

Molecular Weight Threshold

Minimum size for immune recognition of invaders.

Antihistamines

Medications to counteract allergic reactions in immune response.

High Affinity Antibodies

Strongly binding antibodies for effective immune response.

Helper T Cells

Cells that assist in activating B cells and immune response.

Antigen Presentation

Process of displaying antigens to activate T cells.

Professional Antigen Presenting Cells

Cells specialized in presenting antigens to T cells.

• has specific ID

Humoral Immunity

B cell-mediated immunity involving antibody production.

• binds to specific antigen

• ex. antivenom

  • prevents further damage from toxin getting to nerve

B Cell Receptors

Surface proteins that bind specific antigens.

Cellular Immunity

T cell-mediated immune response targeting infected cells.

B Cell Activation

Process initiated by T cells to produce antibodies.

Cytotoxic T cell recognition

Identifies infected cells via HLA and black dots.

Natural Killer (NK) cell recognition

Destroys unhealthy cells lacking proper HLA.

HLA

Human leukocyte antigen, identifies healthy cells.

• black dot = infection/compromise

Cytokines

Chemical messengers regulating immune responses.

• blanket term

• trigger inflammation

Interleukines

Cytokines facilitating communication between white blood cells.

Chemokines

Chemical signals guiding immune cell movement.

Interferons

Cytokines responding to viral infections.

• when you feel sick but dont get sick

Tumor necrosis factor

Cytokine that induces cell death.

• involved in inflammation of autoimmunity

Hematopoietic cytokines

Stimulate production of immune cells.

• control stem cells

Cytokine storm

Excessive immune response causing inflammation.

• body keeps thinking its under attack

Haptens

Small molecules requiring carriers to trigger immunity.

• attaches to skin carrier molecule to get big enough to invade

Hapten-adduct conjugate

Complex formed when haptens bind to carrier molecules.

Poison ivy reaction

Sensitization occurs on first exposure, reaction on second.

• the first time was spent producing antibodies

Penicillin reaction

Can induce hemolytic anemia by altering RBC appearance.

Epitopes

Specific regions on antigens recognized by immune system triggering an immune response

Immunosuppressants

Medications reducing immune response in transplant patients.

Infection susceptibility

Increased risk due to lowered immune function.

Massive inflammation

Result of cytokine storm, causing severe symptoms.

Steroids

Medications used to reduce inflammation in cytokine storms.

Immunoglobulin G (IgG)

Most abundant antibody, 80% of serum antibodies.

Autoimmune

Condition where body attacks its own cells.

Antigen-binding site

Region on antibody that attaches to antigens.

• 4 heavy chains

• 2 light chains

B cells

Adaptive immune cells that produce antibodies.

T cells

Cells required for specific antibody production.

Clumping

Aggregation indicating presence of antibodies.

Memory cells

Long-lasting cells that remember past infections.

IgM

First antibody produced, first to respond

• pentamer structure with J chain

• primitive

• sticky; can attach up to 10 locations

IgA

Antibody found in mucous membranes and breastmilk

• dimer

• 4 valence locations

• blocks attachment of pathogens

IgD

Antibody found on

• B-cell surface

• blood

• lymph

IgE

Antibody involved in allergic reactions

• 0.002% of serum

• crosses placenta

• monomer

• on mast cells, basophils, and in blood

• binds to toxin to prevent tissue from getting damaged

Vasodilation

Widening of blood vessels, often due to IgE.

Histamine release

Response causing allergy symptoms, triggered by IgE.

Primary response

Initial immune response to first exposure to antigen.

• takes 15 days for antibodies to kick in

Secondary response

Faster immune response upon re-exposure to antigen.

• memory cells kick in

Immunotherapy

Treatment to build immunity against allergens.

• Competitiveness of igG vs. igE 

• Increasing igG outcompetes to intercept igE (histamine release; less chance) 

  • IgE = 0.002% 

  • IgG 80% 

Competitiveness of IgG

IgG can outcompete IgE in immune response.

igG

most abundant amount of antibodies

• monomer

• igG booster

• Some goes to placenta to baby, gets protection from mom

MHC

Major histocompatibility complex for organ matching.

HLA MHC complex

Human leukocyte antigen for organ transplant identification.

Class I MHC

Present on all nucleated cells.

Class II MHC

Found on antigen presenting cells (APCs) and B cells

• dendrites, macrophages

Immunosuppressants

Medications that reduce immune response so that T-cell won’t tell macrophage and cytoplasmic t-cell to kill foreign organ 

Crispr Cas9

Gene-editing tool used in transplants.

• UAB pig kidney

Immunotherapy

Treatment aiming to enhance immune response.

Superantigen

Stimulates T cells non-specifically, causing inflammation.

• Helper T and APC do not know what is invading because there is an empty receptor 

• Over 20% T cell is stimulated meaning cytokines are going out = massive inflammation, large number

T-independent antigens

Antigens that can stimulate B cells to produce antibodies without T cell hel

• produces IgD

• no high affinity

• no memory cells come out

Agglutination

Clumping of antigens and antibodies together.

Complement system

Enhances inflammation and lyses pathogens.

Antibody dependent cell mediated cytotoxicity (ADCC)

Mechanism where NK cells kill antibody-coated cells.

• usually for larger pathogens like tapeworms

Neutralization

Antibodies surround toxins to prevent tissue damage.

• snake and spider antivenom

• botox

T cytotoxic cells (CD8+ T cells)

Cytotoxic cell infuses target cell with chemicals and induces apoptosis 

Apoptosis

Programmed cell death induced by cytotoxic T cells.

• Like a switch 

• Self-destruction

Acquired/adaptive immunity

Immunity gained through exposure or vaccination.

naturally acquired immunity

•  immunity acquired naturally through life 

  • Active - getting sick 

  • Passive - breastfeeding, transfer of antibodies 

artificial immunity

• actively seeking and receiving immunity 

  • Active - getting vaccinated 

  • Passive - antibody transfer 

Helper T cells (CD4+-)

Cytokine signaling with B cells; interact directly with antigens

• Bind MHC class II molecules