Activated basophils give lupus a booster shot

Abstract

Basophils have recently been identified as antigen-presenting cells that are required for optimal antibody responses. New findings now show that activation of these cells can amplify autoimmune responses in systemic lupus erythematosus (SLE).

Figure 1

Basophil activation by autoreactive IgE. Peripheral blood basophils are activated by IgE-containing immune complexes (IgE-IC) to upregulate CD62L that allows them to migrate into lymphoid organs. Upregulation of MHC class II (MHC-II) confers antigen-presenting properties, and upregulation of IL-4 promulgates a T_H2 (IL-4–producing) T cell phenotype. IL-4, together with increased basophil cell surface expression of BAFF and increased production of IL-6 from multiple cell types (including basophils), enhances autoantibody class switching to IgG1 that can deposit in the kidneys and IgE that further perpetuates basophil activation. TACI, transmembrane activator and calcium modulator ligand interactor.