Somatic Hypermutation in Activated B Cells

Di Nola and Neuberger (2002) reported that activation-induced deamination (AID) of cytosine to uracil leads to hypermutation.

In this figure, you can see that replacing the NH2 with an O leads to the conversion of C -> U in the variable region of the light and heavy chain gene segments. When the B cells try to repair the resulting mismatch, several outcomes are possible:

These base changes lead to altered binding affinities. Those B cells with improved affinity will be clonally selected and they will proliferate.

References

• Patricia Gearhart. 2002. Nature 419:29.
• Javier Di Nola and Michael S. Neuberger. 2002 Nature 419: 43.