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Abstract: PO1797

Antibody Sequencing Analysis After Flu Vaccine Response in IgA Nephropathy Patients Reveals Enhanced IgA Variable Regions of the Heavy Chains Lineage Diversity

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Reily, Colin, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Knoppova, Barbora, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Fucile, Christopher, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Rosenberg, Alex, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Rizk, Dana, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Julian, Bruce A., University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • Novak, Jan, University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
  • King, Rodney G., University of Alabama at Birmingham, Departments of Medicine and Microbiology, Birmingham, Alabama, United States
Background

IgA nephropathy (IgAN), the most common primary glomerulonephritis in the world, is characterized by mesangial immunodeposits consisting of galactose-deficient IgA1 (Gd-IgA1) and Gd-IgA1-specific IgG autoantibodies. IgG autoantibodies in IgAN patients have variable regions of the heavy chains (VH) with long complementarity-determining region 3 (CDR3) that contains a key amino-acid residue important for binding Gd-IgA1. This CDR3 modification is not due to a genetic variant of a VHgene in IgAN patients but it is thought to originate from somatic mutations. To determine whether IgAN patients have generally enhanced rates of VHsomatic mutations, we have assessed responses to influenza-vaccine antigens in IgAN patients vs. healthy controls.

Methods

Peripheral blood (PB) from 4 IgAN patients and 4 healthy controls (HC) was collected 7 d after flu vaccination (i.m.), the peak of plasmablasts in PB. Plasmablasts were isolated after enrichment with CD138-coated beads. cDNA from plasmablasts was used for VHgene amplification with VH- and isotype-specific primers, and sequenced on an Illumina MiSeq. Sequences were filtered, aligned, and grouped using an in-house workflow, with further analyses performed in Matlab.

Results

Isotype-specific nucleotide mutation rates were similar in IgAN and HC plasmablasts, except for IGHV3-7with a higher rate in HC for IgM (p=0.01). Average nucleotide mutation rate for CDR3 was 1.6% higher in HC compared to IgAN, almost reaching significance (p=0.06). Further analysis revealed that number clonotype-specificVHsequences was increased for IgA in plasmablasts from HC vs. IgAN for IGHV2-5(p=0.02), IGHV3-7(p=0.04), IGHV3-15(p=0.02), IGHV3-21(p=0.01), IGHV3-30 (p=0.01),IGHV3-48(p=0.03), IGHV4-38-2(p=0.05), IGHV4-59(p=0.04), and IGHV4-61(p=0.02).

Conclusion

Analysis of influenza-vaccine-specific immune responses showed that IgAN patients and HC exhibit similar VHnucleotide mutation rates. Unexpectedly, we also observed thatIgAN patients produced fewer IgA VHsequences than healthy controls after flu vaccination, indicating a possible disparity of IgA responses in IgAN.

Funding

  • NIDDK Support