Kappa and Lambda Light chains
Antibodies are made of two identical heavy chains and two identical light chains. The gene rearrangement process, coupled with random assortment of heavy-light chain pairs, creates huge diversity in the B cell repertoire.
Where there is one heavy chain locus for the different genes involved in heavy chain gene rearrangement, there are actually two different loci for the light chains. They are called kappa and lambda. They take it in turns to rearrange. The kappa chain rearranges first. Often, because the gene rearrangement process is not precise, the gene rearrangement will fail. If the kappa loci on both alleles fail to produce a useful kappa gene then the lambda locus will undergo rearrangement. Because of this ordered process we will normally have approximately two thirds kappa and one third lambda in our antibody genes.
In many of our experiments in vitro we have swapped light chains by cloning different ones with the same heavy chain and don’t find that the light chain makes a big difference to the antibody specificity, However, in some of our swaps we saw it did make a difference in the way and antibody bound to a self antigen. This would agree with published data that says light chain swapping - or “Receptor editing” - is an important part of the early B cell development process to avoid autoimmunity.
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