Defective B cell tolerance in adenosine deaminase deficiency is corrected by gene therapy
Aisha V. Sauer, … , Alessandro Aiuti, Eric Meffre
Aisha V. Sauer, … , Alessandro Aiuti, Eric Meffre
Published May 24, 2012
Citation Information: J Clin Invest. 2012;122(6):2141-2152. https://doi.org/10.1172/JCI61788.
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Research Article

Defective B cell tolerance in adenosine deaminase deficiency is corrected by gene therapy

Abstract

Adenosine deaminase (ADA) gene defects are among the most common causes of SCID. Restoration of purine metabolism and immune functions can be achieved by enzyme replacement therapy, or more effectively by bone marrow transplant or HSC gene therapy (HSC-GT). However, autoimmune complications and autoantibody production, including anti-nuclear antibodies (ANAs), frequently occur in ADA-SCID patients after treatment. To assess whether ADA deficiency affects the establishment of B cell tolerance, we tested the reactivity of recombinant antibodies isolated from single B cells of ADA-SCID patients before and after HSC-GT. We found that before HSC-GT, new emigrant/transitional and mature naive B cells from ADA-SCID patients contained more autoreactive and ANA-expressing clones, indicative of defective central and peripheral B cell tolerance checkpoints. We further observed impaired B cell receptor (BCR) and TLR functions in B cells after ADA inhibition, which may underlie the defects in B cell tolerance. Strikingly, after HSC-GT, ADA-SCID patients displayed quasi-normal early B cell tolerance checkpoints, as evidenced by restored removal of developing autoreactive and ANA-expressing B cells. Hence, ADA plays an essential role in controlling autoreactive B cell counterselection by regulating BCR and TLR functions.

Authors

Aisha V. Sauer, Henner Morbach, Immacolata Brigida, Yen-Shing Ng, Alessandro Aiuti, Eric Meffre

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Figure 3

Defective peripheral B cell tolerance checkpoint in ADA-SCID patients before HSC-GT.

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Defective peripheral B cell tolerance checkpoint in ADA-SCID patients be...
(A) Increased frequency of HEp-2–reactive antibodies in ADA-SCID mature naive (CD19+CD10–IgM+CD27–) B cells. Antibodies from mature naive B cells from 2 ADA-SCID patients and HD27 were tested by ELISA for reactivity with HEp-2 cell lysate. Dotted lines show ED38-positive control. Horizontal lines show cutoff OD405 for positive reactivity. The frequencies of HEp-2–reactive and non–HEp-2–reactive clones are summarized in the pie charts, with the number of antibodies tested shown in the center. (B–D) Increased frequency of (B) HEp-2–reactive, (C) polyreactive (tested against dsDNA, insulin, and LPS), and (D) ANA-expressing clones of mature naive B cells of ADA-SCID patients compared with HDs. Each symbol represents an individual, horizontal bars denote means, and dashed lines show the average frequency in HDs. *P ≤ 0.05. (E) Higher frequencies of chromatin-nonreactive, chromatin-reactive, and kinetoplast-reactive clones in ADA-SCID patients than HDs. Values are mean + SEM. *P ≤ 0.05. (F) ANAs from ADA-SCID mature naive B cells show various anti-nuclear staining patterns. 3 examples of ANA-expressing mature naive B cells are shown for each patient. Original magnification, ×40.