Lecture 7 Adaptive Immunity Flashcards
What are the innate lines of defense
1st (physical and chemical) and 2nd (inflammatory response and biological)
What are the adaptive lines of defense
3rd
Humoral or antibody mediated (B cells)
Cell-mediated (T cells)
What is the registry called SELF in the body
A recognition of all the body’s components
How is the SELF determined
By proteins called the major histocompatibility complex (MHC)
- coded by Gene’s (HLA- human leukocyte antigen system)
What does everything that is NONSELF produce
A specific immunological reaction to DESTRUCTION of the invading pathogen
Body specific defences can be specific antigens such as
- foreign substances
- pathogens
- intruders
- nonself
Antigens stimulate a response from
The immune system
Where are most antigens
In lymph nodes and decrease as you move away
What are 2 features of antigens (specific response)
They are a substance that initiate a specific immune response
- Production of antibodies
- Generation of immunocompetent cells
What form can antigens be
Proteins or polysaccharides
- or a combo of both
What is a determinant or epitope of an antigen
Part of the antigen necessary for the production of antibodies
What do you call an incompetent antigen
HAPTEN
- must combine to a protein carrier to become complete
What is the first stage of the development of B cells
Occurs in bursa of fabricius (not in humans)
- tissue in yolks sac and fetal liver early development
- later in red bone marrow
- then Naive B cell (inactive)
- 100000 antibodies on surface, no secretions
- migrate through other lymphoid structures
- negative selection
What Is second stage B cell development
- occurs when antigen is present
- antigen binds to antibody causing rapid mitotic division
- results in clone of identical B cell
- most differentiate into effector B cells (plasma cells)
- some become memory B cells
Features of Effector B cells
- plasma cells
- secrete large amounts of antibodies 2000/sec
- all clones produce same antibody
- short life span -> just a few days
Features of Memory B cells
- stay dormant until contact with antigen -> produce more plasma cells and memory B cells
What are antibodies (immunoglobulins)
- structures that react to antigens
- glycoprotein found in: blood serum (plasma protein) and liquid tissue
What are the 5 different classes of of immunoglobulins
IgM IgG IgA IgE IgD
What is the diversity arises from somatic recombination hypothesis
- rather than one static DNA sequence, multiple fragments are recombined to form individual genes
- since 1 antibody requires multiple proteins, allows for multiple combinations
- can also arise from mutations
What is the structure of antibodies
- 2 heavy chains (3 constant regions, 1 variable region)
- 2 light chains (1 constant, 1 variable)
- 2 complement-binding sites
- held together by various disulfide bonds
What is IgM
~10%
Blood
1st antibody produced in response to an antigen
Capacity to fix the complement
What is IgA
~15%
Milk, saliva, tears, colostrum, mucosa
Prevent penetration
What is IgD
~ trace amount
On surface of B cells
Fixes to antigen
Stimulates B cell to produce antibodies
IgG
~70%
Common, blood and lymph
Only one to cross the placenta
Capacity to fix the complement
What is IgE
~trace
Responsible for allergies
Associated with mast cells & basophils that release histamine
What are the 4 pathways/ mechanism to incapacitate antigens so that they can be devoured by macrophages
- Neutralization (masks dangerous parts of bacterial neurotoxins; viruses)
- Agglutination (cell-bound antigens)
- Precipitation (soluble antigens)
- Complement
What is the antigen presenting complex
- protein complex
- present on dendritic cells, macrophages, active B cells
- their role is secondary ( present a antigen fragment to T cell, helps target cells for destruction and immune adaption)
Quick recap of antigen presenting complex B-cell
Liver (foetus)
Red bone marrow (adult)
20- 30% circulate in the blood
Humoral immunity
Quick recap of antigen presenting complex T-cells
Born of the red bone marrow Matures in the thymus Becomes immunocompetent in the lymphoid organs (adult); 70-80% circulate in the blood Cell mediated immune response
Development of T-cells
- lymphocytes travel to thymus and differentiate into thymocytes
- rapidly divide (3/day) then migrate out of thymus and into T-dependent zones (in lymph nodes and spleen)
- inactive or naive T cells
- become active after contact with APC -> sensitized T cell
- divide rapidly becoming clonal effector or memory T cells
- effector T cells (include cytotoxic, helper, suppressor)
- memory T cell ( migrate to red bone marrow, produce more T cells when activated)
What are 3 types of T cells
- Cytotoxic (killer) T cells
- Helper T cells
- Suppressor T cells
How do cytotoxic (killer) T cells work
Bind to antigens, releass lymphotoxins to kill cells
How do helper T cells work
- regulate B cell and T cell function
- release cytokines that stimulate lymphocytes, phagocytes, and other leukocytes
- activated by antigens, form clones of both effector and memory T cells
How do suppressor T cells
- suppressor B cell differentiation, other T cells
- maintain self-tolerance by reducing T cell responses to self antigens
- allows for antagonistic control of immune response
- help to restore homeostasis after immune response
What is naturally acquired active immunity
Via infection
Contact pathogen / direct
What is naturally acquired passive immunity
Via mother
Transfer of antibody through the placenta or via breast milk
What is artificially acquired active immunity
Via immunization
Vaccine contain dead or attenuated virulent miccroorganisms
What is artificially acquired passive immunity
Via injection of another host’s immune serum (antibodies)
What is the difference between active and passive immunity
The degree of protection
What is degree of protection with passive immunities
Short life (antibodies degrade)
B cells are not stimulated
Immunity memory is not established
What is degree of protection with active immunity
T cells and B cells are stimulated
Immunity memory is established until degraded
What is autograft
Graft of a tissue from one region to another same individual
What is isograft
Graft where the donor is a genetically identical twin
What is allograft
Graft of an individual of the same species (but not identical)
What is xenograft
Graft of an individual of a different species
What are allergies
Intense immune reaction accompanied by lesions in the tissues
- it is fighting against a considerable opponent
What is an allergen
Antigen that does not trigger a normal reaction
What are autoimmune disorders
- loss of the capacity to distinguish between the self and non self
- destruction of ones own tissues
What is multiple sclerosis
- destruction of white matter (myelin) of the brain & spinal cord
- features: vision problems, loss of muscle control, urinary incontinence
What is myasthenia gravis
- block at the neuromuscular junction
- absence of Ach receptors
- Features: fatigue of muscles, difficulty in swallowing and speaking
What is graves (Basedow) disease
-thyroid produces an excessive quantity of tyroxine (hyperthyroidism)
- features: sweating, loss of weight, exophtalmos
-
What is type 1 diabetes mellitus
- insulinodependant/ juvenile
- destruction of B endocrine cells of the pancreas
- features: insulin deficiency, not capable of metabolizing glucose
What is systemic lupus erythematosus
- self-harming immune response (DNA identification)
- systemic disease (kidney, heart, lung, skin)
- obtain: glomerulonephritis, vascular problems, painful arthritis
What is glomerulonephritis
Severely impaired kidney function
What is rheumatoid arthritis
- destruction and inflammation of the joints
- obtain: synovitis, ankylosis
What is AIDS
- acquired immune deficiency syndrome
- caused by immunodeficiency virus (HIV)= Retrovirus
- has RNA that makes it’s own DNA in infected cell
- target’s helper T cells, diminishing proper immune function
- cancer, infections, can spread much faster
- transmit by needle, breastfeeding, sex
- rapid mutation hard to tx
