Somatic mutation of the T15 heavy chain gives rise to an antibody with autoantibody specificity.

Proceedings of the National Academy of Sciences of the United States of America

PubMedID: 6435121

Diamond B, Scharff MD. Somatic mutation of the T15 heavy chain gives rise to an antibody with autoantibody specificity. Proc Natl Acad Sci USA. 1984;81(18):5841-4.
The S107 IgA kappa-chain myeloma cell line makes an antiphosphocholine antibody of the T15 idiotype. A somatic mutant of this line, U4, makes an immunoglobulin with a single amino acid substitution of an alanine for a glutamic acid at residue 35. This single amino acid change results in a loss of phosphocholine binding activity. However, the U4 immunoglobulin has acquired reactivity with a variety of phosphorylated macromolecules, including double-stranded DNA, protamine, and cardiolipin. Thus, a single amino acid change in the T15 heavy chain can transform an antibacterial antibody into an antibody that resembles the autoantibodies seen in mice and man with autoimmune disease.