Lec 20- Adaptive Immunology Flashcards
Adaptive (specific) immunity
Is a specific attack against specific antigens by a small number of B cells and T cells that recognize very specific antigen determinants.
Immunological competence
Ability to produce against non-self antigens while tolerating self-antigens. Occurs during first month of life.
Autoantibodies
Exposure to such self-antigens results in production of autoantibodies.
Autoreactive T cells
Killer T cells that attack self-antigens
Clonal deletion theory
One of 2 mechanisms for tolerance.
Tolerance occurs because T cells that recognize self-antigens are destroyed.
Good evidence of this occurs in thymus.
Clonal anergy
Lymphocytes dircted against self-antigens are present throughout life but don’t attack self-antigens.
Mechanism not understood.
Appears to underlie tolerance in B cells.
Memory cells
When B cells divide, some progeny become memory cells.
Plasma cells
A B cell that makes massive amounts of antibodies.
Some of those B cells division become plasma cells that produce about 2000 antibodies per sec that are specific for original antigen.
This provides active immunity.
Primary response
On 1st exposure to pathogen, there is latency of 5-10 days before specific antibodies aee made.
Antibody level plateau after few days and decline after a few weeks.
Secondary response
Subsequent exposure to same antigen caused secondary response.
Antibody production is much more rapid and sustained.
Apoptosis
Programmed cell death.
Active immunity
Development of a secondary response provides active immunity.
Involves activation of B cells.
Needs to be a min size requirement.
Vaccination
Cause development of B cell clones that can provide secondary response.
Passive immunity
A transfer of antibodies to a person.
I.e. by injection or in mother’s breast milk.
This provides and immediate response, because the persons B cells didn’t make the antibodies, it will only last a short time.
It will NOT prepare the body for a second attack.
Ab/immunoglobins
Antibodies are proteins called immunoglobins. Part of gamma globulin class of plasma proteins.
Heavy chain
Part of antibody structure (which is ‘Y’ shaped).
The ‘v’ part.
Light chain
Part of antibody structure (which is ‘Y’ shaped).
The ‘l’ part.
Fc fragment
When cleaved, the stalk of ‘Y’ becomes crystallizable fragment.
This is CONSTANT among different antibodies.
Fab fragment
Arms of ‘Y’ contain antigen-binding fragment.
Contains a variable region that confers antibody specificity.
Complement system
A collection of plasma proteins that are activated in cascade fashion on exposure to invading microorganisms, ultimately producing a membrane attack complex that destroys the invaders.
Histocompatibility antigens
FIND
HLA - human leukocyte antigens
A histocompatiblity antigen.
Are on surface of all body’s cells except mature RBC’s.
MHC - Major histocompatibility complex
a group of genes that produce 2 different major plasma membrane proteins (class 1 and class 2). Mark our cells as "self".
MHC class I
molecules sample the proteins that are being synthesized inside the cell, and present the peptides to T cells to check to see that the cells have not been infected.
MHC II
can present a foreign peptide to helper T cells to cause them to activate other cytotoxic T cells and B cells to the presence of a foreign pathogen.
Coreceptors
FIND
CD8/Cytotoxic or Killer T cells
Cytotoxic have CD8 on surface. attack any cell wuth either the wrong MHC class 1 molecule or an MHC class 1 molecule with a foreign peptide on it.
CD4/Helper T cells
Helper have CD4 on surface.
Helper T cells will recruit cytotoxic T cells and B cells and help to activate only those cells which will recognize their particular antigen.
Virus
an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.
Autoimmune diseases
Are produced by failure of immune system to recognize and tolerate self-antigens.
Autoreactive T cells are formed and B cells produce autoantibodies.
Afflicts women twice as often as men.
Immune complex diseases
Involve formation of immune complexes that are free and not attached to a cell.
These activate complement proteins and promote inflammation.
Can result form infection by bacteria, parasites, viruses.
Can result from formation of complexes between self-antigens and autoantibodies. This occurs in rheumatoid arthritis and systemic lupus erthematosis (SLE)
Allergy/hyopersensitivity
Is abnormal immune response to allergens.
Immediate
B ell. IgE. Antihistamine.
Is due to abnormal B cell response to allergen; causes effects in secs to mins.
Caused by foods, bee stings, pollen.
Treated with antihistamines.
Delayed
T cell. Corticosteroids.
Is abnormal T cell response that causes symptoms 24-72 hours after exposure.
Treated with cortisol or its derivatives.
