| First Author | Janssen E | Year | 2022 |
| Journal | J Clin Invest | Volume | 132 |
| Issue | 20 | PubMed ID | 36006710 |
| Mgi Jnum | J:331430 | Mgi Id | MGI:7384178 |
| Doi | 10.1172/JCI154487 | Citation | Janssen E, et al. (2022) Immune dysregulation caused by homozygous mutations in CBLB. J Clin Invest 132(20):e154487 |
| abstractText | CBL-B is an E3 ubiquitin ligase that ubiquitinates proteins downstream of immune receptors to downregulate positive signaling cascades. Distinct homozygous mutations in CBLB were identified in 3 unrelated children with early-onset autoimmunity, one of whom also had chronic urticaria. Patient T cells exhibited hyperproliferation in response to anti-CD3 cross-linking. One of the mutations, p.R496X, abolished CBL-B expression, and a second mutation, p.C464W, resulted in preserved CBL-B expression. The third mutation, p.H285L in the SH2 domain of CBL-B, was expressed at half the normal level in the patient's cells. Mice homozygous for the CBL-B p.H257L mutation, which corresponds to the patient's p.H285L mutation, had T and B cell hyperproliferation in response to antigen receptor cross-linking. CblbH257L mice had increased percentages of T regulatory cells (Tregs) that had normal in vitro suppressive function. However, T effector cells from the patient with the p.H285L mutation and CblbH257L mice were resistant to suppression by WT Tregs. Bone marrow-derived mast cells from CblbH257L mice were hyperactivated after FcepsilonRI cross-linking, and CblbH257L mice demonstrated exaggerated IgE-mediated passive anaphylaxis. This study establishes CBL-B deficiency as a cause of immune dysregulation. |
