Recognition of Extra Cellular Pathogens Flashcards
(26 cards)
Discuss pattern recogntion receptors’ distribution
The body has probably around 100, and different cells (e.g. macrophages) can express multiple different PRRs to act on foreign substances
Antigen
Component of an infectious agent for which the body contains a lymphocyte which can recognise it
Epitope
Part of an antigen molecule to which an antibody attaches itself
Surface immunoglobulins vs secreted
B Lymphocytes have many surface immunoglobulins which are all identical; bound to the membrane via a transmembrane region. Once they specialise into plasma cells, these new cells focus on secreting immunoglobulins but have the same exact structure
Only difference is attachment via transmembrane region
Describe clonal selection
It is a competitive process
Describe polypeptide chain distribution in immunoglobulins
2 identical Light Chains, 2 identical Heavy Chains
Each immunoglobulins has identical antigen binding sites since each has a heavy and light chain
Those thick black lines are disulfide bonds (e.g. between the two heavy chains, base of a domain or between heavy and light chain)
VH and VL
Variable domains (heavy and light); region that allows variation between antigen combining sites and different antibodies
Hypervariable region
As the name suggests, the parts of the variable regions that have the most amino acid variation between different antbodies
CH and CL
Constant regions between different immunoglobulins
Hinge Region
Region halfway down the heavy chain that has some flexibility which means that the two arms can move relative to each other
Fab Region and Fc Region (of immunoglobulins)
Fab - region above hinge region that contains light chain, Vh and CH1 of heavy chain
Fc - region below hinge region that contains CH2 and CH3
What are Immunoglobulin classes/subclasses/isotypes and how do they vary from each other
IgM; IgG (1, 2, 3, 4); IgA (1, 2); IgE; IgD
They vary from their constant regions so have different genes that code for each other
**Men get aggressive erectile dysfunction
Genes that encode different types of light chains
Kappa κ or Lamda λ (B cells can use different genes to make its light chain
What gene are B cells programmed to use to form the constant regions of their surface antibodies
The mu gene to make IgM class for heavy chain
Class switching of immunoglobulins
When activated, the B cell changes the genes it expresses to form the constant domains of the newly synthesised heavy chains of new antibodies (e.g. going from mu to epsilon gene [IgM → IgE])
Compare the different immunoglobulin isotypes
IgE has 4 constant domains in the heavy chain
IgM always exists as a pentamer connected by a Joining chain with all antibodies having identical binding sites; can bind up to 10 epitopes
Which Ig Subtypes are concerned with complement activation (C1q binding)
IgM, IgG
Which Ig Subtypes are concerned with Phagocyte Binding (via Fc)
IgG, IgA
Which Ig Subtypes are concerned with Mast Cell Binding
IgE
Which Ig Subtypes are concerned with Natural Killer Cell Binding
IgG
Where can IgM pentamers be found
Blood
Where can IgG monomers be found
Blood, Tissues, placental transfer - much of foetal immunity comes from this maternal IgG
Where can IgA monomers be found
Blood/Tissues
Where can IgA dimers be found
Mucosal secretion, Milk - can give protection to newborns
