Lymphocytes IV Flashcards
How do mature IgM and IgD B lymphocytes differentiate into other isotypes (IgE, IgA, IgG)?
By gene rearrangement mediated by cytokines and CD40 ligands (p.198)
What is the function of IgG?
Serves as the main antibody in secondary (delayed) antigenic response; fixes compliment; opsonizes bacteria; provides infants with passive immunity; neutralizes bacterial toxins and viruses (p.198)
What immunoglobulin type is the main responder in secondary, delayed antigenic response?
IgG (p.198)
What is the most abundant immunoglobulin isotype?
IgG (p.198)
What immunoglobulin isotype crosses the placenta?
IgG (p.198)
What is the function of IgA?
To prevent attachment of bacteria and viruses to mucous membranes (p.198)
In what form does IgA circulate?
As a monomer in circulation (p.198)
What form is IgA in in secretions?
Dimeric form (p.198)
How does IgA cross epithelial cells?
By transcytosis (p.198)
Where is IgA found?
In secretions- tears, saliva, mucous, early breast milk (p.198)
From where does IgA pick up secretory component before secretion?
From epithelial cells (p.198)
What immunoglobulin type is the main responder in the primary, immediate antigenic response?
IgM (p.198)
What is the function of IgM?
Serves as the primary immediate responder to an antigen; to fix complement; to serve as an antigen receptor on the surface of B cells (p.198)
In what forms does IgM circulate?
As a monomer on B cells; as a pentamer otherwise (p.198)
How does the shape of IgM contribute to antigen trapping?
Pentamer shape allows IgM to efficiently trap free antigens out of tissue while the humoral response evolves (p.198)
Where is IgD found?
On the surface of many B cells and in serum (p.198)
What is the function of IgE?
To bind mast cells and basophils. It cross links when exposed to antigen, mediating immediate (type I) hypersensitivity through release of inflammatory mediators such as histamine; Mediates immunity to worms (p.198)
How does IgE contribute to the type I hypersensitivity response?
Through release of inflammatory mediators such as histamine (p.198)
How does IgE mediate immunity to worms?
By activation of eosinophils (p.198)
What type of immunoglobulin is in the lowest concentration in the serum?
IgE (p.198)
What are thymus independent antigens?
Antigens lacking a peptide component that cannot be presented by MHC to T cells (p.198)
Give two examples of thymus independent antigens.
Lipopolysaccharide from cell envelope of gram negative bacteria and polysaccharide capsular antigen (p.198)
What is the function of thymus independent antigens?
To stimulate the release of antibodies without creating immunologic memory (p.198)
What is a thymus dependent antigen?
An antigen containing a protein component (p.198)
Give an example of a thymus dependent antigen.
Diptheria vaccine (p.198)
