What T cell subsets are involved in primary biliary cholangitis?

Primary biliary cholangitis (PBC) is an autoimmune liver disease where the immune system attacks the small bile ducts. T cells, a type of white blood cell, play a central role in this process. Research shows that several different T cell subsets are involved, not just one. The main subsets include CD4+ helper T cells (especially Th17 and regulatory T cells), CD8+ cytotoxic T cells, T follicular helper (Tfh) cells, T peripheral helper (Tph) cells, and unconventional T cells such as γδ T cells, mucosal-associated invariant T (MAIT) cells, and invariant natural killer T (iNKT) cells ⁴⁶⁸.

What the research says

A narrative review on T cell subsets in PBC highlights that an imbalance between Th17 cells (which promote inflammation) and regulatory T cells (Tregs, which suppress inflammation) is a key feature of the disease ⁴. This Th17/Treg imbalance is part of a broader dysregulation among CD4+ T cells. The same review also notes that bile duct-specific CD8+ T cells undergo clonal expansion, meaning they multiply and directly attack the bile ducts ⁴. Additionally, unconventional T cell subsets—γδ T cells, double-negative T cells, MAIT cells, and iNKT cells—show quantitative and functional abnormalities that correlate with disease activity ⁴.

A 2026 study profiled circulating T follicular helper (Tfh) and T peripheral helper (Tph) cells in PBC patients ⁸. Both Tfh and Tph cells were significantly increased in the blood of PBC patients compared to healthy controls. Their frequencies correlated with autoantibody production and with liver enzyme levels (ALT, AST, GGT), suggesting they indicate liver and bile duct damage ⁸. The study also found that Tfh cell frequency was negatively correlated with total protein and albumin levels, linking these cells to impaired liver function ⁸.

Earlier research on the pathophysiology of PBC describes a multi-lineage immune response involving an imbalance between effector and regulatory T cell activity ⁶. This imbalance contributes to progressive biliary injury. The IL-12 pathway, identified through genome-wide studies, is a key signaling pathway involved in T cell differentiation and activation in PBC ⁶.

Other sources in the provided list focus on symptoms (fatigue, pruritus) and treatment (PPAR agonists, seladelpar) rather than T cell subsets, so they are not cited here ¹²³⁵⁷.

What to ask your doctor

• Could my T cell subset profile (such as Th17/Treg balance or Tfh cells) help guide my treatment options?
• Are there any tests available that measure T cell subsets to monitor disease activity or progression?
• How do current treatments for PBC, like UDCA or second-line therapies, affect these T cell subsets?
• Is there any emerging therapy that specifically targets T cell dysregulation in PBC?