- Walter, Jolan E
- Rucci, Francesca
- Patrizi, Laura
- Recher, Mike
- Regenass, Stephan
- Paganini, Tiziana
- Keszei, Marton
- Pessach, Itai
- Lang, Philipp A
- Poliani, Pietro Luigi
- Giliani, Silvia
- Al-Herz, Waleed
- Cowan, Morton J
- Puck, Jennifer M
- Bleesing, Jack
- Niehues, Tim
- Schuetz, Catharina
- Malech, Harry
- DeRavin, Suk See
- Facchetti, Fabio
- Gennery, Andrew R
- Andersson, Emma
- Kamani, Naynesh R
- Sekiguchi, JoAnn
- Alenezi, Hamid M
- Chinen, Javier
- Dbaibo, Ghassan
- ElGhazali, Gehad
- Fontana, Adriano
- Pasic, Srdjan
- Detre, Cynthia
- Terhorst, Cox
- Alt, Frederick W
- Notarangelo, Luigi D
- et al.
The contribution of B cells to the pathology of Omenn syndrome and leaky severe combined immunodeficiency (SCID) has not been previously investigated. We have studied a mut/mut mouse model of leaky SCID with a homozygous Rag1 S723C mutation that impairs, but does not abrogate, V(D)J recombination activity. In spite of a severe block at the pro-B cell stage and profound B cell lymphopenia, significant serum levels of immunoglobulin (Ig) G, IgM, IgA, and IgE and a high proportion of Ig-secreting cells were detected in mut/mut mice. Antibody responses to trinitrophenyl (TNP)-Ficoll and production of high-affinity antibodies to TNP-keyhole limpet hemocyanin were severely impaired, even after adoptive transfer of wild-type CD4(+) T cells. Mut/mut mice produced high amounts of low-affinity self-reactive antibodies and showed significant lymphocytic infiltrates in peripheral tissues. Autoantibody production was associated with impaired receptor editing and increased serum B cell-activating factor (BAFF) concentrations. Autoantibodies and elevated BAFF levels were also identified in patients with Omenn syndrome and leaky SCID as a result of hypomorphic RAG mutations. These data indicate that the stochastic generation of an autoreactive B cell repertoire, which is associated with defects in central and peripheral checkpoints of B cell tolerance, is an important, previously unrecognized, aspect of immunodeficiencies associated with hypomorphic RAG mutations.