Repeated stimulation of CD4 effector T cells can limit their protective function

Area of Science:

• Immunology
• T cell biology
• Infectious disease

Background:

• Chronic infections can lead to CD8 T-cell dysfunction.
• The impact of repeated T cell receptor stimulation on CD4 effector T cell generation remains unclear.

Purpose of the Study:

• To investigate the effect of antigen presentation duration on CD4 effector T cell generation and function.
• To determine the consequences of repeated T cell receptor stimulation on CD4 T cell responses in vitro and in vivo.

Main Methods:

• In vitro culture of CD4 T cells with antigen-pulsed antigen-presenting cells for varying durations.
• In vivo studies involving primary immune responses with antigen replenishment.
• Assessment of CD4 effector cell expansion, cytokine production, migration, and protective immunity during influenza infection.

Main Results:

• Optimum in vitro CD4 effector generation occurred with antigen presentation limited to 2 days.
• Repeated stimulation led to decreased CD4 effector expansion, reduced cytokine production, and altered migration.
• In vivo, repeated stimulation resulted in functionally impaired CD4 effectors that provided no protection against influenza and had impaired B cell help.

Conclusions:

• The duration of antigen presentation critically dictates CD4 effector T cell function.
• Exceeding an optimal threshold of T cell receptor stimulation in vitro and in vivo impairs CD4 effector function and protective immunity.