CD83 Modulates B Cell Activation and Germinal Center Responses

Area of Science:

• Immunology
• Cell Biology

Background:

• CD83 is a dendritic cell maturation marker.
• CD83 expression in B cells, particularly during germinal center (GC) reactions, suggests a role in B cell immunity.
• Previous studies using CD83 knockout mice were confounded by T cell deficiencies.

Purpose of the Study:

• To investigate the specific function of CD83 in B cell activation and GC responses.
• To overcome limitations of global CD83 knockout models by creating a B cell-specific conditional knockout.

Main Methods:

• Generation of a B cell-specific CD83 conditional knockout (CD83 B-cKO) mouse model.
• Analysis of B cell activation, proliferation, and MHC class II/CD86 expression in vitro.
• Assessment of GC responses post-immunization and during Borrelia burgdorferi infection.
• Competitive repopulation assays using mixed bone marrow chimeras.

Main Results:

• CD83 B-cKO B cells exhibited impaired proliferation and defective upregulation of MHC class II and CD86.
• GC analysis revealed a shift in B cell populations, with increased dark zone B cells in CD83 B-cKO mice.
• No significant changes in IgG levels or affinity maturation were observed, but IgE responses were enhanced.
• CD83-deficient B cells showed a competitive disadvantage in GC responses.
• CD83 B-cKO mice displayed defective bacterial clearance and a Th2-skewed response with elevated IgE.

Conclusions:

• CD83 plays a significant role in B cell activation and proliferation.
• CD83 influences the composition of GC B cell populations.
• CD83 modulates IgE antibody production and overall immune response dynamics in vivo.