Learning Objective:

Understand how regulatory T cells maintain self-tolerance, the markers that identify them, and the consequences of FOXP3 deficiency.

Function

Regulatory T cells suppress CD4⁺ and CD8⁺ effector T-cell activity to maintain specific immune tolerance.

Markers:

• CD3
• CD4
• CD25 (IL-2 receptor α-chain)
• FOXP3 (master transcription factor)

Cytokines Produced (Anti-inflammatory):

• IL-10
• TGF-β

Activity

Disease Association — IPEX Syndrome:

• Immune Polyexdocrinopathy Enteropathy, X-linked
• Caused by FOXP3 mutation → failure of Treg development → severe autoimmunity
• Findings include:
  • Intractable enteropathy (diarrhea)
  • Endocrinopathies (especially early-onset diabetes in male infants)
  • Dermatitis
  • Nail dystrophy
  • Multiple autoimmune disorders
• Occurs in male infants (X-linked recessive)

Activity