How the wild things are: comparative T cell phenotyping and memory T cell identification in wild boar and domestic pigs.

Domestic pigs constitute a significant global livestock resource and are increasingly recognized as valuable biomedical models, enabling fundamental research. In contrast, immunological studies on wild boar remain limited. To address this knowledge gap, we conducted a comparative analysis of baseline immune phenotypes in age-matched cohorts of domestic pigs and wild boar. Additionally, we adapted a staining and flow cytometry gating strategy based on human immunophenotyping protocols to define conventional memory T cell subsets in both species, validating this approach through proliferation assays and cytokine expression profiling. Our results demonstrated that wild boar exhibit a decreased frequency of polymorphonuclear neutrophils and natural killer cells in peripheral blood. Swine Leukocyte Antigen class II (SLA-DR) expression was significantly reduced across all professional antigen-presenting cell populations. Furthermore, the proportion of T lymphocytes was elevated in wild boar relative to domestic pigs. The T cell compartment in wild boar was characterized by a pronounced bias toward γδ T cells, accompanied by reduced frequencies of differentiated CD4+CD8α+ αβ T cells and late-stage memory T cells. Notably, these cells still expressed markers indicative of high activation. Our findings highlight intrinsic immunological differences between domestic pigs and wild boar and provide a foundational framework for future functional immunological studies, particularly in the context of infectious disease research and immunization strategies.