Monoclonal antibody generation by controlled immunoglobulin gene rearrangements
摘要
Monoclonal antibodies (mAbs) are essential for various applications including experimental reagents, diagnostics, and therapeutics. Thus, the platform technologies that stably generate antigen-specific mAbs are increasingly crucial. We previously developed a method to generate mAbs, termed the “ADLib system”, utilizing the avian-derived B cell line DT40. Avian immunoglobulin (Ig) genes diversify principally through gene conversion—a kind of homologous recombination. The ADLib system isolates antigen-specific clones from libraries constructed using DT40 cells treated with Trichostatin A (TSA), a histone deacetylase inhibitor that enhances gene conversion frequencies. The obtained antigen-specific clones are cultured without TSA to minimize further diversification. However, low-frequency spontaneous gene conversion still occurs, potentially leading to gradual changes in the specificity of the clones. To address this, we engineered conditional mutants of activation-induced deaminase (AID), the initiator of gene conversion, using auxin-inducible degron system which enables targeted protein degradation via the auxin-dependent ubiquitin-proteasome pathway. The addition of the phytohormone auxin led to the degradation of degron-tagged AID proteins, effectively halting gene conversion. Subsequently, we carried out the ADLib system using these clones and successfully isolated antigen-specific mAbs. These suggest that our AID conditional mutants provide a powerful tool for generating and stabilizing antigen-specific clones isolated by the ADLib system.