CD6 Regulates CD4 T Follicular Helper Cell Differentiation and Humoral Immunity During Murine Coronavirus Infection

Area of Science:

• Immunology
• Virology
• Molecular Biology

Background:

• The T cell receptor CD6 has dual co-stimulatory and co-inhibitory functions during T cell activation.
• Its precise role in regulating T cell responses during viral infections remains unclear.

Purpose of the Study:

• To investigate the function of CD6 in regulating early T cell activation following viral infection.
• To elucidate the mechanisms underlying CD6-mediated regulation of CD4 T cell responses.

Main Methods:

• Utilized CD6-deficient mice infected with a neurotropic murine coronavirus.
• Analyzed T cell activation, expansion, differentiation, and germinal center responses in draining lymph nodes.
• Investigated CD6 binding proteins and T cell receptor signaling strength.

Main Results:

• CD6 deficiency led to enhanced CD4 T cell activation and expansion.
• Increased differentiation of CD4 T cells into T follicular helper cells, accelerating germinal center responses.
• Identified hindered upregulation of Ubash3a, a T cell receptor signaling inhibitor, in CD6-deficient lymph nodes.
• Observed intensified T cell receptor signal strength in CD6-deficient CD4 T cells.

Conclusions:

• CD6 plays a novel immunoregulatory role in limiting CD4 T cell activation and T follicular helper cell differentiation during viral infection.
• CD6 attenuates antiviral humoral immunity by suppressing T cell responses.