A LAGging kiss leaves T cells cold

Thomas T Xu1, Shiv Pillai1

  • 1Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA.

Science Immunology
|August 1, 2025
PubMed

Insights

Lymphocyte-activation gene 3 (LAG-3) inhibits CD4+ T cell activation by disrupting CDε-Lck condensates. This mechanism highlights LAG-3 as a key therapeutic target for treating cancer and autoimmune diseases.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cellular Biology

Background:

  • Lymphocyte-activation gene 3 (LAG-3) is a cell surface receptor expressed on activated immune cells.
  • LAG-3 plays a crucial role in regulating T cell responses and maintaining immune homeostasis.
  • Dysregulation of LAG-3 function is implicated in various pathological conditions, including cancer and autoimmunity.

Purpose of the Study:

  • To elucidate the molecular mechanisms by which LAG-3 modulates CD4+ T cell activation.
  • To investigate the role of CDε-Lck condensates in LAG-3-mediated T cell suppression.
  • To validate LAG-3 as a potential therapeutic target for immune-related diseases.

Main Methods:

  • Co-immunoprecipitation assays to study protein-protein interactions.
  • Confocal microscopy to visualize CDε-Lck condensate formation.
  • Flow cytometry to assess CD4+ T cell activation markers.
  • In vitro assays using T cell lines and primary immune cells.

Main Results:

  • LAG-3 was found to directly interact with CDε-Lck condensates.
  • Disruption of CDε-Lck condensates by LAG-3 leads to the dampening of CD4+ T cell activation.
  • Inhibition of LAG-3 function restored T cell activation in a preclinical model.

Conclusions:

  • LAG-3 negatively regulates CD4+ T cell activation through the disruption of CDε-Lck condensates.
  • Targeting LAG-3 offers a promising therapeutic strategy for enhancing anti-tumor immunity and managing autoimmune disorders.