Class Switch™
Immunoglobulin class switching (or isotype switch) is a biological mechanism that changes a B cell’s production of antibody from one class to another, for example, from IgM to IgG. During this process, the constant region portion of the antibody heavy chain is replaced with a different chain, but the variable region of the heavy chain stays the same. Since the variable region does not change, class switching is not affecting antigen specificity. Instead, the antibody retains affinity for the same antigens, but can interact with different effector molecules.
Antibody Isotype Switch
From the five main immunoglobulin classes (IgG, IgA, IgD, IgE, and IgM) mostly IgG1 has been used for engineering therapeutic antibodies. More recently IgG2, IgG4 as well as engineered hybrids have been used to adjust the recombinant molecules better to the targeted application (e.g. regarding half-life, effector functions).
BioAtla has developed a suite of mammalian expression vectors which allow for easy expression of the same variable domains in the context of different antibody isotypes.
space
CASE STUDY:
Isotype switch from IgM to IgG:
A murine IgM antibody is expressed as chimeric mouse/human IgM (lane 5) and IgG (lane 3) antibody.
Top panel: analysis with anti-IgM antibody Bottom panel: analysis with anti-IgG antibody