Chimeric antigen receptor (CAR) T cell therapies have transformed treatment of B cell malignancies. However, their broader application is limited by complex manufacturing processes and the necessity for lymphodepleting chemotherapy, restricting patient accessibility. We present an in vivo engineering strategy using targeted lipid nanoparticles (tLNPs) for messenger RNA delivery to specific T cell subsets. These tLNPs reprogrammed CD8 ⁺ T cells in both healthy donor and autoimmune patient samples, and in vivo dosing resulted in tumor control in humanized mice and B cell depletion in cynomolgus monkeys. In cynomolgus monkeys, the reconstituted B cells after depletion were predominantly naïve, suggesting an immune system reset. By eliminating the requirements for complex ex vivo manufacturing, this tLNP platform holds the potential to make CAR T cell therapies more accessible and applicable across additional clinical indications.

Conventional dendritic cells (cDC) are professional antigen-presenting cells that induce immune activation or tolerance. Two functionally specialised populations, termed cDC1 and cDC2, have been described in humans, mice, ruminants and recently in pigs. Pigs are an important biomedical model species and a key source of animal protein; therefore further understanding of their immune system will help underpin the development of disease prevention strategies. To characterise cDC populations in porcine blood, DC were enriched from PBMC by CD14 depletion and CD172a enrichment then stained with lineage mAbs (Lin; CD3, CD8α, CD14 and CD21) and mAbs specific for CD172a, CD1 and CD4. Two distinct porcine cDC subpopulations were FACSorted CD1⁻ cDC (Lin⁻CD172⁺ CD1⁻CD4⁻) and CD1⁺ cDC (Lin⁻CD172a⁺ CD1⁺ CD4⁻), and characterised by phenotypic and functional analyses. CD1⁺ cDC were distinct from CD1⁻ cDC, expressing higher levels of CD172a, MHC class II and CD11b. Following TLR stimulation, CD1⁺ cDC produced IL-8 and IL-10 while CD1⁻ cDC secreted IFN-α, IL-12 and TNF-α. CD1⁻ cDC were superior in stimulating allogeneic T cell responses and in cross-presenting viral antigens to CD8 T cells. Comparison of transcriptional profiles further suggested that the CD1⁻ and CD1⁺ populations were enriched for the orthologues of cDC1 and cDC2 subsets respectively.

The immune response elicited by the protective whole‐cell pertussis (wP) versus the less‐protective acellular pertussis (aP) vaccine has been well characterized; however, important clinical problems remain unsolved, as the inability of the currently administered aP vaccine is resulting in the reemergence of clinical disease (i.e., whooping cough). Strong evidence has shown that original, childhood aP and wP priming vaccines provide a long‐lasting imprint on the CD4+ T cells that impacts protective immunity. However, aP vaccination might prevent disease but not infection, which might also affect the breadth of responses to Bordetella pertussis (BP) antigens. Thus, characterizing and defining novel targets associated with T cell reactivity are of considerable interest. Here, we compare the T cell reactivity of original aP and wP priming for different antigens contained or not contained in the aP vaccine and define the basis of a full‐scale genomic map of memory T cell reactivity to BP antigens in humans. Our data show that the original priming after birth with aP vaccines has higher T cell reactivity than originally expected against a variety of BP antigens and that the genome‐wide mapping of BP using an ex vivo screening methodology is feasible, unbiased, and reproducible. This could provide invaluable knowledge towards the direction of a new and improved pertussis vaccine design.