T-helper signals restore B-cell receptor signaling in autoreactive anergic B cells by upregulating CD45 phosphatase activity.
J Allergy Clin Immunol
; 138(3): 839-851.e8, 2016 09.
Article
en En
| MEDLINE
| ID: mdl-27056269
ABSTRACT
BACKGROUND:
We recently identified a human B-cell population that is naturally autoreactive and tolerized by functional anergy (BND cells).OBJECTIVE:
We sought to identify the molecular mechanism of how anergic autoreactive BND cells escape functional anergy and whether this process is altered in patients with lupus.METHODS:
Isolated peripheral blood naive and BND cells were cultured with various stimuli, and their activation status was determined by using an intracellular Ca(2+) mobilization assay. Lyn kinase and Syk activities were assessed by using phospho-flow analysis. CD45 phosphatase activity was determined by using a novel flow-based assay, which takes advantage of the fluorogenic properties of phosphorylated coumaryl amino propionic acid, an analog of phosphotyrosine, which can be incorporated into peptides. Real-time quantitative PCR was used to quantitate LYN, SYK, and CD45 mRNA.RESULTS:
T-helper signals reversed the state of anergy, allowing BND cells to fully respond to antigenic stimulation by restoring signaling through the B-cell receptor (BCR). The mechanism was dependent on increased activity of the tyrosine phosphatase CD45 and CD45-dependent activation of Lyn and Syk. CD45 phosphatase activity was increased by T-cell help both in BND and naive B cells. Furthermore, we found that BND cells obtained from patients with systemic lupus erythematosus exhibited increased CD45 activity and BCR-signaling capacity, thus being less tolerized than BND cells from healthy control subjects.CONCLUSION:
Our findings suggest that CD45 is a key regulator of BCR-signaling thresholds mediated by T-cell help. This raises the possibility that BND cells could represent precursors of autoantibody-secreting plasma cells and suggests a role for these autoreactive B cells in contributing to autoimmunity if not properly controlled.Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Linfocitos B
/
Receptores de Antígenos de Linfocitos B
/
Linfocitos T
/
Antígenos Comunes de Leucocito
Tipo de estudio:
Prognostic_studies
Límite:
Adult
/
Humans
Idioma:
En
Revista:
J Allergy Clin Immunol
Año:
2016
Tipo del documento:
Article