κ Editing Rescues Autoreactive B Cells Destined for Deletion in Mice Transgenic for a Dual Specific Anti-Laminin Ig
We explored mechanisms involved in B cell self-tolerance in a double- and triple-transgenic mouse model bearing the LamH-Cμ Ig H chain conventional transgene and a gene-targeted replacement for a functional Vκ8Jκ5 L chain gene. Whereas the H chain is known to generate anti-laminin Ig in combination with multiple L chains, the H + L Ig binds ssDNA in addition to laminin. Immune phenotyping indicates that H + L transgenic B cells are regulated by clonal deletion, receptor editing via secondary rearrangements at the nontargeted κ allele, and anergy. Collectively, the data suggest that multiple receptor-tolerogen interactions regulate autoreactive cells in the H + L double-transgenic mice. Generation of H + LL triple-transgenic mice homozygous for the targeted L chain to exclude secondary κ rearrangements resulted in profound B cell depletion with absence of mature B cells in the bone marrow. We propose that the primary tolerogen of dual reactive B cells in this model is not ssDNA, but a strongly cross-linking tolerogen, presumably basement membrane laminin, that triggers recombination-activating gene activity, L chain editing, and deletion.
Brady, GF; Congdon, KL; Clark, AG; Sackey, FNA; Rudolph, EH; Radic, MZ; Foster, MH
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