Lecture 6B - Specific Immunity - The Humoral Response (Antigens & Antibodies) Flashcards
What must be done to properly defend the body against attack by a major pathogen?
lymphocytes must be recruited and a specific immune response generates
What is the specific immune system important for?
to defend us against pathogens that are not of the same chemical signatures of the tissues in our body
What happens in autoimmune disease?
the immune system targets out own body tissues
Is specific more internal or external?
internal
What do we want our immune system to do?
specifically recognise the proteins and sugars which uniquely belong to pathogens like bacteria and parasites, while leaving our own vital proteins alone
What did Von Behring find?
exposure of a guinea pig to a sublethal dose of diptheria toxin rendered them immune to subsequent dose that would normally be lethal
What is transferring immunity?
serum from a previously exposed animal could also protect an unexposed animal from the fatal effects of the diptheria toxin
How is the immunity specific?
it only protected against diptheria toxin but not against others
What did Von Behring call the transferrable chemical agents which provided immunity?
antibodies
How can specific immunity act externally?
eyes, gut, mouth, lungs, saliva, bladder, sex organs, maternal milk
How can specific immunity act internally?
blood stream, kidney, liver, brain, heart and other body tissues
What is specific immunity?
a specific response to particular antigens
What are antigens?
substances recognised by the immune system as being ‘non-self’ and which provoke an immune response
What are most antigenic?
irregular, proturburant domains of protein molecules
What might a large polypeptide have?
several antigenic determinant sites - each of which can provoke an immune response
Polysaccharides antigenic?
have a simpler structure than proteins and are less antigenic
What do many successful parasitic organisms have?
surface proteins which are highly glycosylated
this helps to screen antigenic determinants on their surface proteins from the immune system
Antigenicity of regular polymers and metal lattice structures?
very low antigenicity and are useful materials for implants
smoothness does not alert the immune system of their presence
What often does not produce an immune response?
smooth domains
What do parasites do to evade the immune system?
change the sugars on their cells
MW of antigens?
usually large MW substances - proteins
What is an epitope?
each separate antigenic determinant site on a molecule
How can small molecules become antigenic?
after binding to large molecules (proteins)
such small molecules are called haptens
What happens if a drug molecule binds to a white blood cell?
it makes a molecular shape the immune system has not seen before and an immune reaction will lead to lysis of the white blood cell
What is anaphylactic shock?
a severe allergic reaction that occurs in susceptible individuals
What are haptens a problem with?
drug treatment
What does the specific immune response begin with?
the entry of an antigen into the body
What happens when the immune system detects the antigen?
it recognises it as a species that is not part of the body
this enables activation of the immune system
What does activation of the immune system do?
amplifies the number of immune cells and antibodies specifically targeted against the antigen and eliminates it
Humoral mediators of specific immunity?
antibody mediated immunity
antibodies are DIRECTLY responsible for eliminated the antigen
What do antibodies belong to?
the gamma globulin class of proteins called immunoglobulins -
What are immunoglobulins?
the class of proteins which cause immunity of the animal to the toxin
What is cell mediated immunity?
cells are ultimately responsible for eliminating the antigen, requires cell to cell contact to cause cell death
What does humoral immunity involve?
antibodies circulating in the blood and lymph which can recognise foreign molecules
How do antibodies work?
they do not kill cells directly, but can neutralise viruses and toxins or mark cells and parasites for destruction by phagocytic cells
How can immunoglobulins target cells?
from some distance to be destroyed
Classes of antibodies?
IgA IgD IgG IgE IgM
MADGE
IgG?
most abundant antibody class in the blood and is also transferred across the placenta to give additional protection to unborn child
binds toxins
IgA?
secreted in saliva and mother breast milk to give protection when immune system is weak
IgE?
can bind to trigger mast cells and basophils
IgM?
associated with compliment activation and forms almost a snowflake structure with 5 of the Y shapes antibodies connecting to form a weak ring
