Basophils are potent antigen-presenting cells that selectively induce Th2 cells

Area of Science:

• Immunology
• Cell Biology

Background:

• Basophils and mast cells are effector cells in helminth infections and IgE-mediated allergic inflammation.
• Basophils circulate in blood, while mast cells differentiate in peripheral tissues.
• The source of early Interleukin-4 (IL-4) driving T helper 2 (Th2) responses was previously unclear.

Purpose of the Study:

• To review the known functions of basophils in allergy and parasite infection.
• To examine the newly discovered antigen-presenting cell (APC) functions of basophils.
• To discuss the potential clinical implications of basophil-mediated Th2 responses.

Main Methods:

• Review of existing literature on basophil and mast cell differentiation and function.
• Analysis of studies demonstrating basophil capacity for antigen uptake, processing, and presentation.
• Examination of evidence for basophil-derived IL-4 production and its role in Th2 cell induction.

Main Results:

• Basophils are identified as the predominant APCs inducing Th2 responses against helminths and allergens.
• Basophils express MHC class II and CD80/86, process antigens (especially IgE-antigen complexes), and present peptides.
• Ag-pulsed basophils induce Th2 cell development both in vitro and in vivo, distinct from dendritic cell (DC) functions.

Conclusions:

• Basophils contribute significantly to Th2/IgE responses via IL-4 production and MHC class II-peptide presentation to naive CD4+ T cells.
• This function contrasts with the Th1-inducing role of dendritic cells.
• Understanding basophil APC function offers potential clinical applications in allergy and parasitic infection treatment.