Lecture 6 Antibodies Flashcards
What is an antibody
Glycoprotein composed of heavy (H) and light (L) chains produced as a result of introduction of antigen.
What is an immunoglobulin (Ig)
Term used for antibody molecules, BCRs are Igs.
All antibodies are immunoglobulins, but not all immunoglobulins are antibodies
What is the fab fragment
Stands for fragment antigen binding. Part of the antibody molecule involved in binding to the antigen
What is the Fc fragment
Means fragment crystallizable. Fc fragment of antibody binds to Fc receptor present on surface of granulocytes, lymphocytes and macrophages.
What are immunoglobulin classes
Subdivision of immunoglobulin molecules with unique determinants in Fc region of heavy chain
(IgG, IgM, IgA, IgD).
What are immunoglobulin subclasses
Subdivisions of the classes based on differences in heavy chain (IgG1, IgG2, IgG3 and IgG4).
Where is IgG produced and its function
Produced by plasma cells in spleen, bone marrow and lymph nodes
Plays major role in anti-body mediated responses
Where is IgM produced and its function
Produced by plasma cells in spleen, bone marrow and lymph nodes
Major immunoglobulin during primary response
Where is IgA produced and its function
Produced by plasma cells located on mucosal surfaces
Major Ig for secretions
Can agglutinate antigens and neutralises viruses
Attached to a secretory component for transportation (protects from digestion)
Where is IgE produced and its function
Produced by plasma cells located on mucosal surfaces
Triggers release of inflammatory molecules from mast cells, which eliminates invaders
Also mediates type I hypersensitivity, important in immunity to parasitic worms
Where is IgD produced and its function
Found mainly as BCR
Produced by plasma cells in spleen and lymph nodes
Function unclear, may be involved in defence against microbiota.
What greek letters are associated with IgM, IgG, IgA, IgE and IgD
IgM - micro IgG - gamma IgA - alpha IgE - epsilon (e) IgD - delta
Describe the kinetics of the immune response (Primary 4)
The lag phase is the time between the contact of the immunogen and the detection of antibodies in the circulation, activation of B and T cells are occuring
Exponential phase marks a rapid increase in quantity of Abs in circulation
Steady state period where level of synthesis and degradation of Abs is equal
Declining phase - When antibody level in circulation starts to decline
Primary immune response is mainly IgM
Describe the kinetics of immune response (Secondary)
When encountered with the same antigen as before (primary) The secondary response is similar but much greater levels
The lag period is shorter and the antibody levels rise more rapidly to a higher steady state period.
Reason for the higher response is T and B memory cells generated after primary response
IgG main antibody for secondary
Describe the clonal selection theory
The rapid production of highly specific antibodies. People have large variety of B cells with antigen receptors so when the antigen binds to the right one the B cell undergoes clonal profileration (many divisions) and then the progeny mature to plasma cells which then synthesises many antibodies specific to the antigen first bound.
