T Cell Specific BOB.1/OBF.1 Expression Promotes Germinal Center Response and T Helper Cell Differentiation.

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• The transcriptional co-activator BOB.1/OBF.1 is expressed in both B and T lymphocytes.
• Conventional BOB.1/OBF.1 deficient mice exhibit a complete absence of germinal centers (GCs), primarily attributed to B cell defects.
• The specific role of BOB.1/OBF.1 in T cells regarding the GC reaction remains unclear.

Purpose of the Study:

• To investigate the in vivo function of BOB.1/OBF.1 in CD4+ T and follicular T helper (TFH) cell subpopulations.
• To determine the contribution of T cell-specific BOB.1/OBF.1 expression to the GC reaction.

Main Methods:

• Conditional mutagenesis was employed to delete BOB.1/OBF.1 in CD4+ T and TFH cells.
• Experiments were conducted in the presence of immunocompetent B lymphocytes.

Main Results:

• Deletion of BOB.1/OBF.1 in CD4+ T cells and TFH cells led to impaired GC formation.
• This indicates that the defective GC reaction in conventional BOB.1/OBF.1-deficient mice is not solely due to B cell defects.
• BOB.1/OBF.1 is essential for the differentiation of T helper (TH) cell subsets, especially TFH cells.

Conclusions:

• BOB.1/OBF.1 plays a significant role in T cells, contributing to the GC reaction.
• The findings necessitate a re-evaluation of the exclusive attribution of GC defects to B cell compartments in BOB.1/OBF.1 deficiency.
• BOB.1/OBF.1 is critical for TFH cell differentiation and function.