69:
Naïve B cells are prone to develop into polyreactive autoantibody secreting cells from adult RAG2-deficient patient with combined immunodeficiency
Saturday, March 3, 2018
South Hall A2 (Convention Center)
Matthew T. Stowell, Undergraduate Student, Jolan E. Walter, MD PhD FAAAAI, Thomas C. Pennix, student, Boglarka Ujhazi, Gail Mueller, Manish Butte, Elisabeth G Hoyte, Joseph D. Hernandez, MD PhD, Eric RF Meffre, Krisztian Csomos, PhD
RATIONALE:

Hypomorphic mutations in recombination-activating genes 1 and 2 (RAG1/2) cause a wide spectrum of clinical disease, including combined immunodeficiency with granuloma and/or autoimmunity (CID-G/AI) phenotype. Among these patients, we and others have published the presence of autoantibodies targeting wide variety of antigens including cytokines. Based on animal models, we identified several tolerance checkpoint impairments that may contribute to the generation of autoreactive B cells. Although, it is unclear if autoreactive-prone B cells are already enriched in early naïve stage or develop only after T-B cell interaction and specific antigen exposure among patients.

METHODS:

B cells were isolated using anti-CD20 magnetic beads from peripheral blood of an RAG-deficient patient with CID-G/AI phenotype and age matched healthy controls; sorted for mature naïve B cell compartment (live CD19+CD38midCD24midCD27IgM+CD10) and cultured in the presence of CD40L/IL-21/CpG (TLR9 agonist) and low IgG fetal bovine serum to promote transition to antibody secreting cells (ASCs). On day 7, supernatant was tested for immunoglobulin levels and autoantibodies targeting ssDNA and cytokines (IFNα, IFN-ω, IL-12) by enzyme-linked immunosorbent assay.

RESULTS:

Mature naïve B cells from RAG-deficient patient produced higher level of IgG/IgM immunoglobulins in comparison to healthy controls and patient B cells produced autoantibodies targeting ssDNA and cytokines.

CONCLUSIONS:

Upon in vitro activation, mature naïve B cells from partial RAG2-deficient patient demonstrated higher responsiveness to differentiate into ASCs, even in the absence of T cell help or exposure to specific antigens. In partial RAG deficiency, break in early tolerance checkpoint likely contributes to the generation to autoreactive B cell pool.