T2-Systems_Immunity Flashcards
Body’s system that defends against foreign invaders (antigens)?
Immune system
Name some invaders
bacteria, viruses, other organisms, foreign bodies/substances, abnormal molecules and cells that develop abnormally in the body (cancerous cells)
What are bacteria, viruses, etc?
microbes
What tends to kill or damage microbes?
Antimicrobial substances (e.g. lysosomal enzymes released by immune cells)
What is a specific discrete component of an antigen that attracts immune responses?
Epitope (marked by an antibody or MHC - major histocompatibility complex)
What is a collected coordinated response of the cells and molecules of the immune system to protect against infectious disease?
Immune response
What are the two responses of the immune system?
Innate and Adaptive
What is the innate response of the immune system?
A general response; first line of defence:
- we are born with it
- rapid, early response
- always the same
- primarily reacts to microbes
- relies on phagocytes and antimicrobials
- includes external physical barries like skin/mucous membranes
- utilizes fever, inflammation, etc.
- fairly easy for microbes to adapt to it
- stimulates adaptive response
What is the first line of defense?
Skin and mucous membranes:
- sebum, mucous, hair, tears and saliva
What is the second line of defense?
AKA internal defenses
include:
- antimicrobial substances (interferons, the complement system, iron-binding proteins and antimicrobial proteins), natural killer (NK) cells, phagocytes
What is the complement system?
System that triggers adaptive response (series of cascading events)
What is the adaptive response?
A specific response; develops with exposure to organism/substance:
- slower, develops in reaction to specific attributes of invader
- works with innate processes to enhance reactivity
- attacks microbes and antigens
- generates immunologic memory - subsequent exposures lead to a more rapid response
- typically what is meant by the term “immune system”
What are the primary cells of the immune system?
B-Lymphocytes (B-cells) and T-Lymphocytes (T-cells)
What do lymphocytes do?
Act as Regulator cells (assist in controlling the orchestration of the immune response) and as Effector cells (kill/eliminate microbe or antigen)
What are accessory cells?
Phagocytes: macrophages, neutrophils, eosinophils) that break apart an invader
What are dendritic cells?
Present antigens/epitopes to killer cells
What is humoral immunity?
The immune cells and other immune material (like antibodies) that are circulating in the blood and lymph.
Where else are immune cells located?
- lymph nodes
- spleen
- skin
- mucosa
- vital organs
B-cells
- key players in humoral immunity
- very good at recognizing antigens and microbes
- produce antibodies
- when activated, they select the type of clone needed.
What is a fully mature B-cell called and what does it do?
It’s called a Plasma cell. Plasma cells produce and secrete antibodies- aka immunoglobulins (IgG, IgM, IgA, IgE and IgD)
What do antibodies do?
Bind to epitopes and either kill/neutralize the invader or present them to T-cells or macrophages.
What do some B-cells become?
Memory cells, which do not participate in the initital immune response, but stay in the body to respond quickly if a second exposure to the same antigen occurs.
IgG
“general”
- 70-80% of antibodies
- only Ig to cross placenta
- antiviral, antitoxin, antibacterial actions
- activates killer cells and complement system
IgA
“milk at IGA”
- predominant in breast milk, tears, saliva, nasal/respiratory secretions
- blocks entry of organisms to eyes, gut, respiratory and urinary tracts
IgM
“immediate”
- early responder
- first Ig formed after immunization
- activates complement system
- doesn’t leave lymph or blood; forms natural ABO blood antibodies
IgD
- present in small amounts
- needed for B-cell maturation
IgE
“tinee”
- tiny amounts in plasma
- binds to mast cells and liberates histamines and other inflammatory substances - involved in allergic/hypersensitivity reactions
What is an antigen-presenting cell?
Cells that bind to/break down antigens. B-cells, macrophages and dendritic cells all act as presenting cells.
T-cells
- responsible for cell-mediated (cellular) immunity
- secrete messenger compounds that communicate with immune system cells, which:
- attracts cells
- prevent cells from leaving the area
- amplify effectiveness
- increase or decrease reactions
- activate and regulate B-cells
- signal natural killers
- increase local blood flow to facilitate immune cell movement
- determine if humoral or cellular immunity is needed
Which cells are involved in self vs. non-self recognition and reaction
T-cells
Describe the 2 types of immunity (and each level within)
1- Innate
2- Adaptive
a. Natural: Passive (from Mom) and Active (via infection)
b. Artifical: Passive (antibody transfer) and Active (dead/weak antigen)
What is the mounting of an immune response against the body’s own tissues?
Auto-immunity
Why does auto-immunity happen?
- The microbe might have similar characteristics to the attacked body tissue
- Exposure to a microbe or foreign tissue (like breast implant)
- Over response of immune activities (eg. rheumatoid arthritis, MS, etc.)
- Reduced T-cell suppressor response
What are auto-antibodies
Self-antibodies involved in auto-immunity:
- e.g. MS (auto antibodies attack myelin sheaths in CNS)
What binds with what to create immune complexes?
Auto-antibodies with self molecules
What can happen with mistaken targeting of self cells as dangerous?
Can happen with drugs and viruses that have altered cellular markers
How many types of hypersensitivity reactions are there?
There are 4
T/F: Autoimmune diseases are typically more common in women than men?
True (may be related to hormones)
Which hypersensitivity reaction is mediated by IgE which leads to release of inflammatory mediators from mast cells?
Type 1: Immediate Hypersensitivity
What are characteristics of Type I: Immediate Hypersensitivity?
- begins rapidly
- mediated by IgE
- referred to as Allergic Reactions
- vary in severity (mild/annoying - seasonal allergies, severely debilitating- asthma, life threatening - anaphylaxis)
What are local/atopic reactions to Type I: Immediate Hypersensitivity?
- Allergic rhinitis: edema and hypersecretion of mucosal lining
- Asthma: lung disorder characterized by bronchoconstriction, edema and increased secretion of thick mucous of bronchi
- Urticara (hives): local wheals and erythema in dermis, associated with pruritis (itchiness), develops rapidly after exposure, ingested or through skin
- Angioedema: generalized edema of skin, lips, face, tongue, pharynx
- Gastrointestinal food allergies: reaction in the GI tract, symptoms - nausea, vomiting, abdominal cramps, diarrhea, less common than skin reactions
What are systemic/anaphylatic reactions to Type I: Immediate Hypersensitivity?
- acute, characterized by pruritis, generalized flusing, headache, difficulty breathing, drop in blood pressure (which leads to shock and loss of consciousness)
- caused by smooth muscle contraction and vascular dilation
- common allergens: pollens, food, chemicals, insect stings, drugs.
Tx: epinephrine, subcutaneously
What are characteristics of Type II: Antibody-Mediated Hypersensitivity?
- mediated by IgG and IgM
- characterized by formation of antibodies directed against blood cells, and their destruction
- Erythroblastiosis Fetalis: hemolytic disease in babies which occurs if mother is Rh- and fetus is Rh+ in subsequent pregnancies
- Blood transfusion reactions: when incompatible blood type is administered, manifests as fever, chills, renal failure
- Autoimmune Hemolytic Anemia: antibodies produced by person’s own body are responsible for hemolysis of erythrocytes, manifests as anemia
- Autoimmune Thrombocytopenia: antibodies against platelets, manifests as petechiea (small hemorrhages), purpura (bruising), mucosal bleeding
What is pruritis?
itching
What is purpura?
bruising
What are characteristics of Type III: Immune Complex-Mediated Hypersensitivity?
- mediated by formation of antigen-immunoglobulin complexes, complement fixation, and localized inflammation
- involves IgM and IgG
- immune complexes formed in circulation produce damage when contact with blood vessel lining
- Arthus Reaction: local necrosis response
- Serum Sickness (eg. Penicillin) : systemic response, caused by animal serum or drugs, antigen-antibody complex formed
- Glomerulonephritis: acute streptococcal infection responsible for formation of antibodies, form immune complex, causes inflammation of glomerular membrane, symptoms include: hematuria and proteinuria
- Polyarteritis nodosa: inflammation and necrosis of medium-sized arteries, antigen can be penicillin or Hep B virus, whole body affected
What is hematuria
Blood in urine
What is proteinuria
Protein in urine
What are characteristics of Type IV: Delayed or Cell-Mediated Hypersensitivity?
- mediated by sensitized T-cells
- manifests as sub-acute or chronic inflammation, with infiltration of tissue by lymphocytes and macrophages:
- Contact Dermatitis: acute or chronic delayed on skin surface, caused by plants, drugs, bugs, cosmetics, dyes, paints, jewelry. Manifests as: skin erythema, edema, pruritis and vascular eruption.
- Graft Rejection: Due to delayed hypersensitivity reaction, chronic inflammation with infiltration of graft with infiltration of tissue by lymphocytes and macrophages
