L16-B cell development and the functions of antibodies Flashcards
What is an epitope?
The molecular structure on the antigen that is recognised by the binding site on the antibody.
What are the 5 classes of antibodies and what determines which class they fall into?
The 5 classes are IgM, IgG, IgA, IgD and IgE. They are defined by the structure of the constant region of their heavy chains. This also defines their function.
What antibodies have subclasses?
IgG has 4 subclasses and IgA has two subclasses
What is the main effector function of antibodies mediated through?
Fc region, when antigen bings to the antibody the Fc region acts as a target for the Fc receptors on phagocytes.
What are the 6 main functions of antibodies?
Opsonisation
Neutralisation
Precipitation (immune complex formation)
Complement activation (classical pathway)
Direct Cell activation by Fc receptors
Antibody dependent cell mediated cytotoxicity
How do antibodies help to neutralise pathogens?
By binding to some of the antigens on the pathogen this helps to prevent the pathogens from docking to cells and gaining access. antibodies can also bind and neutralise toxins.
What are immune complexes and how to do they help fight infection?
An immune complex is when antigen molecules interact with several immunoglobulins to form a latticework. This prevents the diffusion of the pathogen
How do antibodies activate complement?
The binding of antibody to antigen causes the classical pathway of complement to be activated.
What is antibody dependent cell mediated cytotoxicity?
It is a mechanism whereby an effector cell e.g. an NK cell or macrophage lyses a target cell that has been opsonised. This is also key for eosinophils killing helminths such as worms.
