Pre-existing Activation States Shape Functional Heterogeneity of Human Vγ9Vδ2 T Cells
γδ T cells are gaining prominence in cancer immunotherapy due to their ability to target tumors. However, their diverse nature has presented challenges to clinical application. Recent research published in Frontiers in Immunology in February 2026, sheds light on the pre-existing activation states that influence the functional heterogeneity of Vγ9Vδ2 T cells, offering crucial insights for optimizing these cells for therapeutic purposes.
Understanding Vγ9Vδ2 T Cell Heterogeneity
Researchers at the University Medical Center Utrecht in the Netherlands investigated the heterogeneity of Vγ9Vδ2 T cells by analyzing the function and gene expression of single-cell clones expanded in vitro. The study revealed that these cells aren’t a homogenous population, but rather exhibit a spectrum of activation states even before in vitro expansion.
Two Distinct Effector Profiles: HIR and LIR
The study identified two primary effector profiles within the Vγ9Vδ2 T cell compartment: high interferon gamma (IFN-γ) releasing (HIR) and low-IFN-γ-releasing (LIR) clones. Even as traditional culture conditions using interleukin (IL)-2 and IL-15 are known to enhance the type 1 effector program, these conditions only polarized a portion of the cells towards the “classic” type 1 effector state.
Unexpectedly, a substantial fraction of the clones exhibited a LIR profile, activating a type 2-like effector program characterized by the secretion of IL-4 and IL-5 and expression of the transcription factor GATA3. This suggests a previously underappreciated functional diversity within Vγ9Vδ2 T cells.
Transcriptional Programs and Activation States
The research demonstrated coordinated transcriptional programs linking effector function to genes associated with T-cell activation, proliferation, and cytokine production. HIR clones displayed a more activated transcriptional profile in culture compared to LIR clones. Importantly, analysis of ex vivo single-cell transcriptomic data revealed that these effector states already exist in vivo, forming a continuous activation landscape within non-expanded Vγ9Vδ2 T cells.
LIR States Predominate in Early Life and Adulthood
The study found that LIR-like states were predominant in cord blood and remained prevalent in adult peripheral blood. This indicates that the functional divergence observed after in vitro expansion isn’t solely due to culture-induced polarization, but rather a stabilization and amplification of pre-existing activation states.
Implications for Cancer Immunotherapy
These findings have significant implications for current γδ T-cell-based cancer immunotherapy strategies. The dominance of a pre-existing LIR-like activation state suggests that current approaches relying on in vivo stimulation or ex vivo engineering may need to be re-evaluated to account for this inherent heterogeneity. Understanding and potentially modulating these pre-existing activation states could be key to enhancing the efficacy of γδ T-cell therapies.
Further Research
Further investigation into the intrinsic signaling features that modulate effector differentiation within this activation continuum is warranted. Analyzing the Vγ9Vδ2 T-cell receptor repertoire may provide additional insights into the factors governing these diverse functional outcomes.