IL-33-activated dendritic cells induce an atypical TH2-type response

Area of Science:

• Immunology
• Cell Biology
• Cytokine Signaling

Background:

• Interleukin-33 (IL-33), an IL-1 family cytokine, is known to promote T helper 2 (TH2) responses.
• The specific immune cells targeted by IL-33 have not been fully elucidated.

Purpose of the Study:

• To investigate if dendritic cells (DCs) are cellular targets of IL-33.
• To determine if IL-33-stimulated DCs can induce TH2-type cytokine production in naive T cells.

Main Methods:

• Dendritic cells were generated from mouse bone marrow.
• Expression of the IL-33 receptor, ST2, was analyzed using flow cytometry and RT-PCR.
• DC activation by IL-33 was assessed by measuring surface marker (MHC-II, CD86) and cytokine (IL-6, IL-12) production.
• The capacity of IL-33-treated DCs to prime naive CD4+ T cells was evaluated through co-culture experiments and cytokine analysis.

Main Results:

• Dendritic cells express ST2 mRNA and protein, with ST2 protein localized intracellularly.
• IL-33 stimulation upregulated MHC-II and CD86 expression and induced IL-6 production in DCs, but not IL-12.
• Anti-ST2 antibody partially inhibited IL-33-induced IL-6 production.
• IL-33 alone did not stimulate naive T cells, but DCs activated by IL-33 induced robust production of IL-5 and IL-13 from naive CD4+ T cells.

Conclusions:

• Dendritic cells directly respond to IL-33 via the ST2 receptor.
• The interaction between IL-33 and dendritic cells represents a potential new mechanism for initiating TH2-type immune responses.