Immunology Flashcards
Define antigen
a foreign substance that induces an immune response
Define agglutinogen
an antigen that stimulated the production of an agglutinin
Define immunogen
any antigen that is capable of producing a humoral and/or cell-mediated immune response
Define hapten
a small molecular weight compound that is unable to stimulate an immune response unless bound to a carrier
Define epitope
a single area on an antigen where a specific antibody can bind
(one antigen can have multiple epitopes)
Define avidity
the overall binding strength between an antibody and antigen
Define affinity
strength of an antibody-antigen interaction
Define specificity
the degree to which an immune response discriminates between antigenic determinants
Define cross-reactivity
reaction of one antigen with antibodies developed from a different antigen
Define monoclonal
a pure antibody produced by a single clone of cells
detects one, specific epitope
Define polyclonal
a collection of antibodies produced by different B-cell lineages
(identify multiple epitopes on the same antigen)
6 things that can help enhance agglutination
Centrifugation Enzyme treatment Colloidal media LISS, PEG, Polybrene Chemically modified antisera Antiglobulin test
How does centrifugation enhance agglutination?
Compacts the cells and antibodies together allowing closer interations
How does enzyme treatment enhance agglutination?
the enzymes partially digest the cell membrane to better expose the antigens
How does colloidal material enhance agglutination?
adsorbing the antigen or antibody onto a larger inert particle
How does LISS, PEG, and Polybrene enhance agglutination?
promote agglutination via decreasing the zeta-potential
How does chemically modified antisera enhance agglutination?
they contain a known antibody to detect unknown antigens
How does the antiglobulin test enhance agglutination?
reduces the zeta-potential by binding to human IgG that is bound to an antigen on the RBCs, which makes the agglutination visible.
3 cellular antigens important in blood bank
Blood group antigens Histocompatibility antigens (HLAs) Antigens and autoantibodies
5 factors that play a role in antigenicity
degree of foreignness degradability molecular weight structural stability complexity
List the following from most antigenic to least antigenic:
lipids, carbohydrates, proteins, nucleic acids
(Most) proteins, carbohydrates, lipids, nucleic acids (Least)
Classes of immunoglobulins
IgG, IgA, IgM, IgE, IgD
Functions of immunoglobulins:
bind antigens
complement fixation
placental transfer
serve as antigen
Structure of IgA in secretions?
dimer (held together via J-chain)
Which immunoglobulin is bound to the surface of immature and mature B-cells?
IgD
Which immunoglobulin is able to cross the placenta?
IgG
Define:
natural antibody
immune antibody
natural antibody: occurs naturally through evolution
immune antibody: formed via stimulation (i.e. pregnancy, transfusions)
Which immunoglobulin is a pentamer in structure?
IgM
Which immunoglobulin is predominant in primary immune response?
IgM
Which immunoglobulin is predominant in anamnestic (secondary) immune response?
IgG
Which immunoglobulin makes up roughly 10% of total Ig?
IgM
Which IG make up 70-75% of the total Ig?
IgG
Which Igs have subclasses and how many subclasses do they have?
IgG has 4 subclasses
IgA has 2 subclasses
Which Ig requires at least two of them to bind in order to activate complement?
IgG
Which Ig needs enhancement to agglutinate in vitro?
IgG
Which Ig is predominant in secretions?
IgA
IgA make up what percent of total Ig?
15-20%
Which Ig activate complement?
IgM and IgG
NOT IgA
What is zeta-potential?
RBCs have a net negative charge and repel each other. They will only get within 25 nm of each other.
Zeta potential refers to pulling the RBCs together to visualize agglutination
Which Ig is best at agglutination?
IgM
How big are IgG molecules?
14 nm
How big are IgM molecules?
45nm
What is Prozone, postzone, and the zone of equivalence?
Prozone: excess antibody (no agglutination)
Postzone: excess antigen (no agglutination)
Zone of equivalence: equal amounts of antibody to antigen (lattice formation)
Why is the secondary immune response shorter?
memory cells
