Bob1 limits cellular frequency of T-follicular helper cells.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• T follicular helper (Tfh) cells are critical for adaptive humoral immunity, mediating B cell antibody production.
• Transcription factors like B-cell lymphoma-6 and Blimp-1 are known regulators of Tfh cell lineage commitment.
• The precise mechanisms governing Tfh cell population size and function remain incompletely understood.

Purpose of the Study:

• To investigate the role of the transcriptional coactivator Bob1 in the development and regulation of Tfh cells.
• To determine if Bob1 influences Tfh cell identity, proliferation, or survival.
• To elucidate the intrinsic mechanisms controlling Tfh cell numerical frequency.

Main Methods:

• Analysis of Tfh cell populations in Bob1-deficient (Bob1(-/-)) and wild-type (WT) mice following immunization.
• Adoptive transfer experiments using Bob1(-/-) CD4(+) T cells into WT recipients.
• In vitro proliferation and cell death assays of Tfh cells stimulated with anti-CD3/CD28 antibodies.

Main Results:

• Bob1(-/-) mice exhibited significantly higher percentages of Tfh cells compared to WT mice after antigen immunization.
• T-cell-intrinsic mechanisms in Bob1(-/-) CD4(+) T cells led to an increased frequency of Tfh cells.
• Bob1(-/-) Tfh cells demonstrated enhanced proliferative capacity and resistance to CD3-induced cell death in vitro.

Conclusions:

• Bob1 plays a critical role in restricting the numerical expansion of T follicular helper cells.
• Bob1 functions intrinsically within Tfh cells to limit their proliferation and maintain homeostasis.
• These findings reveal a novel Bob1-dependent regulatory mechanism controlling Tfh cell frequency upon T cell receptor (TCR) stimulation.