Coformulation with Tattoo Ink for Immunological Assessment of Vaccine Immunogenicity in the Draining Lymph Node.

Characterization of germinal center B and T cell responses yields critical insights into vaccine immunogenicity. Nonhuman primates are a key preclinical animal model for human vaccine development, allowing both lymph node (LN) and circulating immune responses to be longitudinally sampled for correlates of vaccine efficacy. However, patterns of vaccine Ag drainage via the lymphatics after i.m. immunization can be stochastic, driving uneven deposition between lymphoid sites and between individual LN within larger clusters. To improve the accurate isolation of Ag-exposed LN during biopsies and necropsies, we developed and validated a method for coformulating candidate vaccines with tattoo ink in both mice and pigtail macaques. This method allowed for direct visual identification of vaccine-draining LN and evaluation of relevant Ag-specific B and T cell responses by flow cytometry. This approach is a significant advancement in improving the assessment of vaccine-induced immunity in highly relevant nonhuman primate models.

Phenotypic and functional characterization of pharmacologically expanded Vγ9Vδ2 T cells in pigtail macaques.

While gaining interest as treatment for cancer and infectious disease, the clinical efficacy of Vγ9Vδ2 T cell-based immunotherapeutics has to date been limited. An improved understanding of γδ T cell heterogeneity across lymphoid and non-lymphoid tissues, before and after pharmacological expansion, is required. Here, we describe the phenotype and tissue distribution of Vγ9Vδ2 T cells at steady state and following in vivo pharmacological expansion in pigtail macaques. Intravenous phosphoantigen administration with subcutaneous rhIL-2 drove robust expansion of Vγ9Vδ2 T cells in blood and pulmonary mucosa, while expansion was confined to the pulmonary mucosa following intratracheal antigen administration. Peripheral blood Vγ9Vδ2 T cell expansion was polyclonal, and associated with a significant loss of CCR6 expression due to IL-2-mediated receptor downregulation. Overall, we show the tissue distribution and phenotype of in vivo pharmacologically expanded Vγ9Vδ2 T cells can be altered based on the antigen administration route, with implications for tissue trafficking and the clinical efficacy of Vγ9Vδ2 T cell immunotherapeutics.