MONITORING AND INTERPRETING THE INTRINSIC FEATURES OF SOMATIC HYPERMUTATION

We have used both normal and transgenic mice to analyse the recruitmen t and targeting of somatic hypermutation to the immunoglobulin loci. W e compare methods for analysing hypermutation and discuss how large da tabases of mutations can be assembled by PCR amplification of the rear ranged V-gene flanks from the germinal centre B cells of normal mice a s well as by transgene-specific amplification from transgenic B cells. Such studies confirm that hypermutation is preferentially targeted to the immunoglobulin V gene with the bcl6 gene, for example, escaping t his intense mutational targeting in germinal centre B cells. We review our data concerning the nature of the hypermutation domain and the ta rgeting of hotspots within that domain. We consider how enhancer-media ted recruitment of hypermutation to the immunoglobulin loci operates i n a clonally maintained fashion and illustrate how both the degree of expression and demethylation of the transgene broadly correlate with i ts mutability.