New Tool Tracks T Cell Adaptation Across Organs

Researchers develop a system to precisely monitor how T cells respond to infections in different parts of the body.

Published on Mar. 6, 2026

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Researchers at The Rockefeller University and Biohub have created a new tool called TRACK (Tracking Recently Activated Cell Kinetics) that allows scientists to permanently tag and follow recently activated T cells as they travel between organs and adapt their responses during an infection. Using this system, the team studied how T cells in the lungs, lymph nodes, and spleen mount and maintain a defense against the flu virus, revealing a strategic division of labor among these locations.

Why it matters

Understanding how T cell responses evolve across different tissues is crucial for designing more effective immune-based therapies for conditions like cancer, autoimmune diseases, and infections. The TRACK system provides a powerful new tool to precisely map these dynamics and uncover patterns that could lead to better ways to redirect immune function.

The details

The TRACK system works by tagging recently activated T cells with a fluorescent protein, allowing researchers to track how these cells travel and change during an infection. The team used TRACK to study CD4+ T cells, which coordinate the broader immune response, in the lungs, lymph nodes, and spleen of mice infected with the flu virus. Their data revealed that the tissue where T cells first encounter the virus shapes their specialized roles - lung T cells become frontline defenders, lymph node T cells focus on helping B cells make antibodies, and spleen T cells act as mobile reserves. Over time, these populations redistribute and converge into a shared immune memory.

  • The researchers examined the labeled T cells 9 days after infection, when the immune response was at its peak.
  • The researchers examined the labeled T cells again 56 days after infection.

The players

Roham Parsa

First author of the study, group leader of Immune Cell Dynamics and Function at Biohub in New York, and adjunct assistant professor in Rockefeller's Laboratory of Mucosal Immunology.

Daniel Mucida

Head of the Laboratory of Mucosal Immunology at The Rockefeller University and an affiliated investigator at the CZ Biohub NY.

TRACK

A new tool developed by researchers at The Rockefeller University and Biohub that allows scientists to permanently tag recently activated T cells with a fluorescent protein to track how they travel and change during an infection.

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What they’re saying

“The T cell response is compartmentalized in a very elegant way. By mapping how these programs change from tissue to tissue, we can begin to design strategies to precisely redirect immune function.”

— Roham Parsa, Group leader of Immune Cell Dynamics and Function at Biohub in New York and adjunct assistant professor in Rockefeller's Laboratory of Mucosal Immunology (Mirage News)

“Because there are so many T cells already present, you can't home in on only the particular cells you're interested in.”

— Daniel Mucida, Head of the Laboratory of Mucosal Immunology at The Rockefeller University and an affiliated investigator at the CZ Biohub NY (Mirage News)

What’s next

The researchers expect to use the TRACK system to study T cell responses in other conditions like cancer, vaccine responses, and autoimmune diseases, which could reveal new patterns and lead to better ways to redirect immune function.

The takeaway

The TRACK system provides a powerful new tool to precisely map how T cell responses evolve across different tissues during an infection, revealing a strategic division of labor that could inform the development of more effective immune-based therapies.