Repeated Plasmodium falciparum infection in humans drives the clonal expansion of an adaptive γδ T cell repertoire | Anouk von Borstel et al. | ResearchPod

Transcript: Repeated Plasmodium falciparum infection in humans drives the clonal expansion of an adaptive γδ T cell repertoire

Alex: Welcome to another episode of ResearchPod. Today we're looking at a study that challenges how we think about immune memory in malaria. Sam, what's the core puzzle?

Sam: We've long known that γδ T cells respond to malaria, but the field has treated them as a monolithic, innate population — stable, invariant, not really learning. This paper argues that one subset, Vδ1+, is actually an adaptive, evolving arm of the immune response. More like conventional memory T cells than anyone expected.

Alex: So the paper is asking whether repeated Plasmodium falciparum infections actively remodel these cells into something specialized?

Sam: Exactly. The framing is that repeated exposure acts as a selective pressure. Each infection drives the Vδ1+ compartment further from a naive state and toward a clonally expanded, cytotoxic effector phenotype. And the authors suggest this slow remodeling process might be exactly why clinical immunity to malaria takes years of exposure to acquire.

Alex: That's a meaningful reframe. The dominant model has been Vγ9/Vδ2+ cells as the "first responders" — fast, innate-like, invariant. Where do Vδ1+ cells fit relative to that?

Sam: Think of them as occupying a different niche entirely. The Vγ9/Vδ2+ population is stable across repeated infections — it reacts quickly but doesn't fundamentally change. The Vδ1+ compartment, by contrast, undergoes dynamic, individual-specific clonal remodeling over time. The paper frames them as "specialized recruits" rather than standing infantry.

Alex: And the study design — how do they actually isolate this remodeling from the noise of natural exposure in the field?

Sam: That's where the controlled human malaria infection model becomes critical. Rather than relying solely on naturally exposed cohorts, they track individuals through four sequential experimental infections under controlled conditions. That lets them map the trajectory of the Vδ1+ compartment with a precision you simply can't achieve in a field setting, where exposure history is messy and unmeasured.

Alex: So what does that trajectory actually look like?

Sam: Each infection drives a new wave of clonal expansion in the TCR repertoire. But it's not just expansion in numbers — it's functional maturation. The cells shift phenotype, acquiring expression of perforin and granzymes. They become cytotoxically competent. The load-bearing evidence here is the longitudinal TCR tracking: you can watch the repertoire being progressively "tuned" across infection episodes, which is exactly what you'd expect from an adaptive process, not an innate one.

Alex: That distinction matters. An innate response reacts; an adaptive one learns. And the TCR repertoire data is what lets them make that claim?

Repeated Plasmodium falciparum infection in humans drives the clonal expansion of an adaptive γδ T cell repertoire

Anouk von Borstel, Priyanka Chevour, Daniel Arsovski, Jelte M M Krol, Lauren J Howson, Andrea A Berry, Cheryl L Day, Paul Ogongo, Joel D Ernst, Effie Y H Nomicos, Justin A Boddey, Edward Giles, Jamie Rossjohn, Boubacar Traore, Kirsten E Lyke, Kim C Williamson, Peter D Crompton, Martin S Davey

Dec 1, 2021·5:49·pmc·Original Paper

MalariaImmunologyVaccine DevelopmentPlasmodium falciparumγδ T cellsControlled Human Malaria Infection (CHMI)

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6 min

Briefing

Research Question

While innate-like Vγ9/Vδ2+ T cells are known to respond rapidly to malaria, the role of the broader γδ T cell compartment—specifically Vδ1+ T cells—in the development of clinical immunity to Plasmodium falciparum remains poorly understood. This study investigated how repeated malaria exposure influences the phenotype, clonality, and function of these T cell populations in both naturally exposed individuals and a controlled human malaria infection (CHMI) model.

Approach

The researchers conducted a longitudinal analysis of Malian children and adults living in a malaria-endemic region, comparing them to malaria-naive Australian controls. To define the precise impact of P. falciparum, they also monitored five malaria-naive U.S. adults who underwent four sequential controlled malaria infections (CHMI). The team utilized flow cytometry to track T cell subset differentiation and single-cell TCR sequencing to monitor clonal dynamics within the γδ T cell repertoire over time.

Main Findings

The study reveals that the human γδ T cell compartment undergoes significant remodeling in response to malaria. While Vγ9/Vδ2+ T cells maintain a stable, innate-like polyclonal repertoire, the Vδ1+ compartment exhibits adaptive-like features. Specifically, repeated P. falciparum infections drive the differentiation of naive Vδ1+ cells into cytotoxic Vδ1effector cells. These Vδ1effector cells undergo waves of clonal selection, with new TCR clonotypes emerging after each infection. Furthermore, Vδ1+ T cells from individuals with prior malaria exposure were found to be primed for proliferation upon re-stimulation with parasite extracts, suggesting they acquire functional reactivity to the pathogen.

Why It Matters

These findings challenge the traditional view that γδ T cells function solely as innate-like responders. By demonstrating that Vδ1+ T cells exhibit adaptive-like properties—including clonal expansion and differentiation into cytotoxic effectors—this research identifies a previously underappreciated component of the human immune response to malaria. This adaptive-like behavior may contribute to the gradual acquisition of clinical immunity in endemic regions, offering a new target for future vaccine and therapeutic strategies.

Key Terms and Definitions

Vδ1+ T cells — A subset of γδ T cells that typically reside in tissues and exhibit adaptive-like properties, such as clonal expansion, in response to chronic infection.
Vγ9/Vδ2+ T cells — The dominant subset of γδ T cells in human blood that respond rapidly to non-peptidic metabolites (like HMB-PP) produced by P. falciparum.
CHMI — Controlled Human Malaria Infection, a clinical trial model where volunteers are intentionally exposed to malaria parasites to study immune responses in a highly regulated setting.
Vδ1effector — A differentiated state of Vδ1+ T cells characterized by high cytotoxic potential (e.g., expression of perforin and granzymes) and a CD27lo CX3CR1+ phenotype.
Clonal Selection — The process by which specific T cell clones expand in frequency following antigen encounter, leading to a more focused and specialized TCR repertoire.

Abstract

Malaria drives the adaptive differentiation of the human γδ T cell repertoire.

Repeated Plasmodium falciparum infection in humans drives the clonal expansion of an adaptive γδ T cell repertoire: Research Paper Podcast