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Orientation regulation of class-switch recombination in human B cells

Authors

  • L. Du
  • V. Oksenych
  • H. Wan
  • X. Ye
  • J. Dong
  • A.Y. Ye
  • H. Abolhassani
  • S. Vlachiotis
  • X. Zhang
  • K. de la Rosa
  • L. Hammarström
  • M. van der Burg
  • F.W. Alt
  • Q. Pan-Hammarström

Journal

  • Journal of Immunology

Citation

  • J Immunol 213 (8): 1093-1104

Abstract

  • We developed a linear amplification-mediated high-throughput genome-wide translocation sequencing method to profile Ig class-switch recombination (CSR) in human B cells in an unbiased and quantitative manner. This enables us to characterize CSR junctions resulting from either deletional recombination or inversion for each Ig class/subclass. Our data showed that more than 90% of CSR junctions detected in peripheral blood in healthy control subjects were due to deletional recombination. We further identified two major CSR junction signatures/patterns in human B cells. Signature 1 consists of recombination junctions resulting from both IgG and IgA switching, with a dominance of Sµ-Sγ junctions (72%) and deletional recombination (87%). Signature 2 is contributed mainly by Sµ-Sα junctions (96%), and these junctions were almost all due to deletional recombination (99%) and were characterized by longer microhomologies. CSR junctions identified in healthy individuals can be assigned to both signatures but with a dominance of signature 1, whereas almost all CSR junctions found in patients with defects in DNA-PKcs or Artemis, two classical nonhomologous end joining (c-NHEJ) factors, align with signature 2. Thus, signature 1 may represent c-NHEJ activity during CSR, whereas signature 2 is associated with microhomology-mediated alternative end joining in the absence of the studied c-NHEJ factors. Our findings suggest that in human B cells, the efficiency of the c-NHEJ machinery and the features of switch regions are crucial for the regulation of CSR orientation. Finally, our high-throughput method can also be applied to study the mechanism of rare types of recombination, such as switching to IgD and locus suicide switching.


DOI

doi:10.4049/jimmunol.2300842