Older Donors’ Immune Cells Show Distinct Galectin Response to Dengue Virus in Lab Study

Older adults with dengue face higher risks of adverse outcomes, but the contribution of age-related immune responses remains uncertain. A laboratory study published in Virology Journal compared how immune cells from older and middle-aged donors respond when exposed to dengue virus serotype 2 (DENV-2) in culture. The researchers found that cells from older donors released higher amounts of two soluble proteins, galectin-3 and galectin-9, at later time points, while concentrations of most other measured mediators were generally lower.

The study used peripheral blood mononuclear cells (PBMCs) drawn from volunteer donors: ten older donors aged 65 years or above, with a median age of 74.9 years and an observed range of 65.8 to 92.0 years, and ten middle-aged donors, with a median age of 39.4 years and an observed range of 34.8 to 49.1 years. In the laboratory, the PBMCs were exposed to the DENV-2 strain TH-36 at a multiplicity of infection of 5.

To track the immune response over time, the team collected culture supernatants before exposure and at 24, 48, and 72 hours after DENV-2 exposure. They then measured nine soluble mediators: GM-CSF, IFN-γ, IL-6, IL-10, MCP-1, TNF-α, and VEGF-A, along with galectin-3 and galectin-9.

The most pronounced differences emerged late in the culture period. Compared with cultures from middle-aged donors, cultures from older donors had higher galectin-3 concentrations at both 48 and 72 hours. At 48 hours, the median galectin-3 concentration was 363.6 pg/mL in older donor cultures versus 197.8 pg/mL in middle-aged donor cultures, with an exploratory p value of 0.0412. By 72 hours, the gap widened: 810.1 pg/mL versus 218.5 pg/mL, with a p value of 0.0011.

Galectin-9 followed a similar late pattern. At 72 hours, older donor cultures showed a median concentration of 219.6 pg/mL compared with 92.23 pg/mL in middle-aged donor cultures, a difference that reached a nominal p value of 0.0355. The reported differences in galectin-9 were concentrated at this late time point.

In contrast to the galectins, the seven other measured mediators were generally lower in older donor cultures across the 24 to 72 hour window. The authors also noted that IFN-γ, IL-10, and TNF-α differed between the groups even at baseline, before any virus was introduced, indicating that some differences in circulating immune mediator levels were already present in the donors’ blood.

The authors frame these findings as exploratory. The between-group p values at each time point were unadjusted comparisons, and interpretation of the nominal significance levels is limited by the small sample size of ten donors per group and by the multiple comparisons performed across nine mediators and four time points. The study also did not test statistical associations between cytokine and galectin concentrations, so the relationship between the two patterns remains an open question.

There are further limits on what the results can tell us. The experiments used an ex vivo culture model, in which isolated PBMCs are exposed to virus in a dish rather than within the full complexity of a living immune system. This design cannot establish causal mechanisms or clinical outcomes, and the findings may not translate directly to how older patients respond to dengue infection in the body.

Despite these caveats, the study makes a methodological point: the authors conclude that the contrasting pattern highlights the value of examining galectins alongside other soluble mediators when investigating variation in responses to DENV-2. A measurement strategy limited to the standard cytokine panel would not have captured the elevated galectin concentrations observed in the older donor cultures.

According to the authors, the small sample and the culture model limit causal and clinical inference, and larger donor-linked experiments and studies in patients with dengue are needed to assess the reproducibility and clinical relevance of the findings. Until such studies are conducted, the reported differences in galectin-3, galectin-9, and the seven other mediators remain an ex vivo observation rather than an explanation of clinical outcomes in older adults with dengue.

Subject of Research: Age-related differences in soluble immune mediators after ex vivo DENV-2 exposure of PBMCs

Article Title: Higher late galectin-3 and galectin-9 amid lower cytokine concentrations in DENV-2-exposed PBMC cultures from older versus middle-aged donors

Article References: Lee, I.-K., Kuo, Y.-H., Tsai, C.-C., Tsai, C.-Y., Hsu, J.-C., & Chen, Y.-C. (2026). Higher late galectin-3 and galectin-9 amid lower cytokine concentrations in DENV-2-exposed PBMC cultures from older versus middle-aged donors. Virology Journal. https://doi.org/10.1186/s12985-026-03343-7

Image Credits: AI Generated

DOI: 10.1186/s12985-026-03343-7

Keywords: dengue virus, DENV-2, galectin-3, galectin-9, cytokines, PBMC, aging, ex vivo culture, immune response, Virology Journal, Higher, late