Mark H. Kaplan, PhD, DFAAI, will give a Distinguished Lecture, “Counting to Nine: The Amazing Adventures of the Ninth Interleukin,” on Saturday, April 18, at IMMUNOLOGY2026™. Dr. Kaplan is Nicole Brown Professor of Immunology and Director of Basic Science at the Brown Center for Immunotherapy of the Indiana University School of Medicine.
Kaplan served as Editor-in-Chief of ImmunoHorizons from 2020 to 2024. He was named a Distinguished Fellow of AAI in 2025 and is receiving the AAI Distinguished Service Award this year. Much of his work has focused on understanding the function of transcription factors in the development of T helper cell subsets. He has a longstanding interest in Signal Transducer and Activator of Transcription (STAT) proteins that are activated downstream of cytokines. His more recent work has made great progress towards understanding the development and function of IL-9-secreting T cells in the development of allergic inflammation.
We spoke with Dr. Kaplan about his upcoming Distinguished Lecture as part of a series of interviews with IMMUNOLOGY2026™ speakers.
How would you describe your talk to a non-specialist in 30 seconds?
Cytokines are like the cell phone signal of the immunology world. It’s all about who can send the signal and who can receive it. Despite being discovered more than 30 years ago, IL-9 is still somewhat mysterious. We’ve done a fairly good job of understanding what cells produce it, but which cells respond to it in the context of specific immune responses is still not well understood.
My talk will provide an in depth understanding of the current state of IL-9 biology and describe multiple scenarios where IL-9 plays an obligate role in inflammation and immunity.
What was the path that led you to the research you are discussing in your talk? What development in this field are you most hopeful for in the near future?
The path started by examining transcription factors in T cells and defining how they contribute to generating cell fate. We surprisingly found that one other the factors we were studying regulated IL-9.
The work progressed from understanding what cells make IL-9 and how IL-9 is controlled, to what cell respond to IL-9 and how that defines pathologic and beneficial immune responses.
What advice would you give someone about to embark on the amazing adventure of becoming an immunologist?
Bring a jacket. At least that’s what my grandmother always told me.
Immunology is an amazing field where we are still developing our appreciation for the intricacies of immune responses and at the same time seeing that it lies at the core of so many diseases where immune manipulation could benefit humanity.
We have an amazing toolkit to interrogate disease models and to analyze patients receiving immune modulatory therapies. The wealth of possibilities makes it an amazing time to be an immunologist.
What can we look forward to at your “Deeper Dive”?
I’ll talk about work that defines a novel IL-9R complex and about integrating our observations of how IL-9-responding cells in contribute to inflammation and immunity in various pathologic contexts.
What is your favorite part of the AAI annual meeting?
The best part is always seeing friends and colleagues and talking to new collaborators. And finding out new information that makes you think “wow, I did not know that.”
Should we expect to see the classic green sunglasses make an appearance?
Thanks for bringing this up. With uncertainty in funding, I will be auctioning off the opportunity to take a picture with me in the classic green sunglasses. Details to be released soon. All proceeds will go to support immunology research!
