Immune System - Lecture 4 Part B Flashcards
What do heavy chain isotopes mean?
Different chains can combine to form different antibody classes or isotopes
What are the different types of antibodies?
IgM, IgD, IgG, IgE, IgA
Which type of antibodies are the first to be produced during an immune response?
IgM antibodies
Why do IgM antibodies tend to be low affinity?
Because they are the first to be produced during an immune response and haven’t gone through affinity maturation yet or class switching yet
What do IgM antibodies do?
They activate the complement system inducing cell lysis and cause agglutination
What are the most common antibodies found in our serum?
IgG antibodies
How do IgG antibodies work?
They bind to active receptors and enhance phagocytosis by macrophages. AKA cause opsonization
What is unique about IgG?
It is considered an Opsin because it enhances phagocytosis by macrophages
Aside from opsonization, what can IgG induce?
ADCC or antibody dependant cellular cytotoxicity
How can we tell whether somebody has a present or past infection?
We can measure the IgM and IgG levels in the plasma. If they are high then there is probably a current infection
What is IgE known for its role in?
Allergy, Asthma, worm and parasitic infections. Sometimes venoms
Why is IgE made it very small quatities?
Because it is very potent and leads to degranulation of eosinophils, basophils and mast cells
Where are IgD antibodies found and why?
In high levels in the upper respiratory tract where they react with pathogens that usually infect us using those roots
Where are IgA antibodies found?
They are found in circulation but are more abundant in secretions and mucous membrane
What do IgA antibodies do in blood?
Stimulate phagocytosis and trigger degranulation. They also stimulate ADCC
What does IgA do in secretions?
They neutralize toxins and pathogens by enhancing their clearance from out body
How does IgA reach the lumen of our intestinal tract?
Through transcytosis that is stimulated by a polypeptide chain
What are the 6 effector mechanisms produced by antibodies?
- Neutralization
- Agglutination
- Opsonization
- Complement system activation
- NK cell recruitment
- Degranulation
In what form can antibodies not gain access to pathogens?
They cannot access pathogens that live inside infected cells
How does the Neutralizing effector mechanism work?
Neutralizing antibodies bind to pathogens preventing them from crossing our epithelial barrier
How does the Agglutination effector mechanism work?
Antibodies agglutinate pathogens facilitating their clearance and preventing them from binding to our cells. Also helps to attract phagocytic cells to eliminate them
What is Opsonization?
The process of coating microbes for subsequent phagocytosis
How does Opsonization by antibodies work?
Antibodies bind to an antigen or pathogen leaving their FC region free allowing phagocytes which have FC receptors to recognize the antibody and create signals to enhance the phagocytosis
What is antibody dependent cellular cytotoxicity?
When NK cells express x receptors that bind to IgG antibodies, attach to the surface of an infected cell and create signals causing the NK cell to degranulate
What are the two ways that NK cells can recognize their targets?
MHC I molecules and antibodies binding sites
How do antibodies eliminate worms?
They stimulate neutrophils and macrophages to degranulate
