Engineered Antibody Class Switch Recombination

Background

Class switch recombination (CSR) occurs during the normal maturation of B-cells. The initial step of CSR is the binding of an antigen to the B-cell surface-expressed immunoglobulin (Ig) H. Provided that the proper cytokines are present, antigen binding sets off a sequence of biological events that eventually lead to different mature B-cell populations each displaying or secreting antibodies of different classes. These classes reflect changes in the constant region of the antibody while the variable (antigen binding) region remains unaltered. The different classes of antibodies elicit differential interactions between host factors and the variable constant regions permitting the immune system to respond to the same antigen through distinct mechanisms. However, inducing CSR in vitro is time consuming, sometimes requiring multiple sequential B-cell cultures in the presence of different cytokines.

Technology Overview

Researchers at Boston Children’s Hospital have developed an alternative approach to inducing CSR. Instead of the traditional cytokine B-cell culture approach, the researchers have employed CRISPR/Cas9 gene editing technology and guide RNA molecules designed to induce specific class changes. These class changes can be induced in both naïve B-cells and hybridoma without the need for time-consuming and expensive cell cultures in a sequence of conditions. In addition to the CSR work, the researchers also successfully induced Fab fragment production in B-cells and hybridoma. Together, this set of methods allows straightforward, one-step approaches to manipulate antibodies and their classes for therapeutic and research purposes. The techniques and reagents developed by the researchers are ideally positioned to deliver significant gains in the workflow efficiency of antibody providers.

Further Details

• Cheong TC, et al. Editing of mouse and human immunoglobulin genes by CRISPR-Cas9 system. Nat Commun. 2016 Mar 9;7:10934.
• Gostissa M, et al. IgH class switching exploits a general property of two DNA breaks to be joined in cis over long chromosomal distances. Proc Natl Acad Sci USA. 2014 Feb 18;11(7):2644-9.

Benefits

• More time and cost efficient than traditional cytokine approaches to inducing CSR.
• Fab fragment production from the same hybridoma/B-cell line as the antibody.

Applications

Production of antibodies with identical epitopes with any desired constant region or without a constant region.