Human switch region sequencing

Switch regions of the human immunoglobulin (Ig) heavy chain locus on chromosome 14 were sequenced to determine DNA-insertions originating from distant genomic loci and chromosomes. Previously, a switch insertion of an exon plus flanking intronic sequences of the LAIR1 gene from chromosome 19 has been shown to generate bispecific antibodies with broad reactivity to the Malaria causing parasite Plasmodium falciparum in African donors (doi: 10.1038/nature16450). Splicing of the LAIR1-exon between the JH and CH1 segments gave rise to an extra immunoglobulin-like domain that became the critical antibody binding element. Here, polyclonal naïve B cells or class-switched IgA+/IgG+ memory B cells of European blood donors were analyzed to detect frequency and origin of templated sequence insertions in switch recombination joints.