{
  "abstract": "Background Adoptive cell transfer (ACT) therapies have demonstrated clinical success across a range of hematological malignancies. However, ACT’s broader application is limited by the low frequency of neoantigen-specific immune cells and the reliance of ex vivo T cell priming on autologous dendritic cells. Accordingly, our group previously developed a paramagnetic artificial antigen presenting cell (aAPC) platform that recapitulates antigen-specific T cell activation by presenting peptide-loaded MHC (Signal 1) and costimulatory anti-CD28 (Signal 2). 1 However, current artificial ex vivo T cell expansion platforms – including ours – omit other immunologically-relevant molecular cues. In particular, ICAM-1/LFA-1 interactions in the peripheral supramolecular activation cluster have been shown to enhance T cells sensitivity to cognate antigens and promote differentiation. Additionally, these interactions regulate T cell localization, adhesion, and extravasation into tumors. Herein, we augment the aAPC platform with ICAM-1 to improve ex vivo T cell activation, more accurately replicating native immunological signaling.Methods aAPCs were constructed and validated using a 250 nm paramagnetic nanoparticle platform composed of an iron oxide core and dextran coat, as described previously.1 Murine CD8+ T cells were collected from the lymph nodes and spleens of C57BL/6 mice. Naïve CD8+ T cells were incubated with aAPCs for enrichment and expansion of antigen-specific T cells (figure 1A). After expansion (7 days, unless otherwise stated), the TCR specificity, phenotype, effector function, and memory profiles of cells were assessed via immunostaining.Results Three aAPC formulations were evaluated ( figure 1B). These particles were applied to enrich and expand a small SIY-specific population from naïve CD8+ T cells. After 7 days, these groups expanded antigen-specific populations of 21.0%, 9.09%, and 35.5%, respectively (figure 2A). Triple-signal particles also produced the lowest proportion of PD-1+ cells (12.2% vs. 56.1%) (figure 2B), while maintaining similar frequencies of effector and central memory phenotypes (figure 2C). ICAM-1-functionalized particles also exhibited improved fold-proliferation of T cells (figure 3).Subsequently, constructing aAPCs to selectively present individual cues, we co-delivered ICAM-1-only particles alongside signal 1 and 2 particles. Applying a continual magnetic field during ex vivo expansion facilitated SMAC-like organization and enhanced T cell expansion.Conclusions This approach more accurately replicates immunological synapse dynamics and isolates the signaling role of LFA-1. In following experiments, we hypothesize ICAM-1-mediated interactions may be leveraged to magnetically enrich for higher LFA-1 expression and migratory/infiltration competence. Broadly, these findings underscore the physiological significance of APC signaling molecules beyond the conventional signals 1 and 2.Acknowledgements B.B. is supported by the Quad Fellowship and the American Australian Association Graduate Education Scholarship. B.B. and C.T. would like to thank everyone in the Schneck Lab for their support. Special thanks to Shweta Singh for assistance in the production and purification of H-2Kb:Ig protein used in all experiments.Reference Omotoso MO, Lanis MR, Schneck JP. Artificial antigen-presenting cell fabrication for murine T cell expansion. Current Protocols 2024;4(2):e976. https://doi.org/10.1002/cpz1.976Ethics Approval The study has obtained the required ethics approval for working with the used mouse models. The ethics committee from which approval was obtained is the Animal Care Use Committee (ACUC). The approved protocol number is MO22M199.Abstract 318 Figure 1Abstract 318 Figure 2Abstract 318 Figure 3",
  "authors": [
    {
      "affiliations": [
        "Johns Hopkins University, Baltimore, MD, USA"
      ],
      "name": "Benjamin Biggs"
    },
    {
      "affiliations": [
        "Johns Hopkins University, Baltimore, MD, USA"
      ],
      "name": "Clayton Tomlinson"
    },
    {
      "affiliations": [
        "Johns Hopkins University, Baltimore, MD, USA"
      ],
      "name": "Jonathan P Schneck"
    }
  ],
  "title": "318 Augmenting artificial APCs with ICAM-1 to enhance CD8+ T cell expansion for anti-cancer immunotherapy",
  "uid": "81601973-35ad-5047-b873-27a5b641fe7a"
}