Cutting edge: Th2 response induction by dendritic cells: a role for CD40.

Area of Science:

• Immunology
• Cell Biology

Background:

• T helper (Th) cell differentiation is crucial for adaptive immunity.
• Dendritic cells (DCs) are key antigen-presenting cells that direct T cell responses.
• The role of DC CD40 in directing Th1 versus Th2 polarization remains incompletely understood.

Purpose of the Study:

• To investigate the specific role of dendritic cell (DC) CD40 expression in the development of Th1 and Th2 immune responses.
• To determine whether DC CD40 is required for initiating Th2 responses to soluble egg antigen (SEA) from Schistosoma mansoni and Th1 responses to Propionibacterium acnes.

Main Methods:

• In vivo transfer of antigen-pulsed bone marrow-derived DCs from wild-type (WT) and CD40(-/-) mice.
• Assessment of Th1 and Th2 responses following DC transfer.
• Analysis of immune responses in CD154(-/-) mice following direct antigen challenge.

Main Results:

• CD40(-/-) DCs failed to induce Th2 responses when primed with SEA, and did not induce compensatory Th1 responses.
• CD40(-/-) DCs successfully generated a Th1 response when primed with P. acnes.
• CD154(-/-) mice lacked Th2 responses to schistosome eggs but mounted normal Th1 responses to P. acnes.

Conclusions:

• Dendritic cell CD40 expression is a critical prerequisite for the initiation of Th2 immune responses.
• Th1 immune responses can be initiated independently of dendritic cell CD40 signaling.
• The CD40-CD154 interaction plays a significant role in the induction of Th2 responses.