VLP-Open HLA nanoparticles enable high-throughput T cell screening and activation

Understanding and manipulating T cell responses is crucial for developing therapies in cancer immunotherapy and autoimmune diseases. MHC-I proteins are central to this, presenting intracellular peptides to CD8+ T cells and dictating their activation or anergy. Current methods for studying these interactions, such as using autologous antigen-presenting cells (APCs), are often labor-intensive, costly, and suffer from variability. There's a significant need for standardized, high-throughput platforms to efficiently screen for novel T cell receptors (TCRs) and induce specific T cell activation, overcoming the limitations of primary cell systems and accelerating therapeutic discovery.

Researchers developed VLP-Open HLA, a multivalent, loadable platform based on a virus-like particle (VLP). This platform was engineered to display up to 60 peptide/HLA (human leukocyte antigen) molecules simultaneously. The VLP-Open HLA nanoparticles were then utilized in two primary applications: first, for staining antigen-specific CD8+ T cells to identify orphan TCRs; and second, when combined with costimulatory molecules, as an artificial antigen-presenting platform to induce antigen-specific T cell activation and expansion. The design allows for adaptation to encompass multiple HLA allotypes and various costimulatory molecules, creating mosaic nanoparticles for diverse immunological studies.

The VLP-Open HLA platform successfully demonstrated its capacity to display a high valency of peptide/HLA molecules, specifically up to 60 per particle, which is critical for robust T cell engagement. This multivalent display enabled efficient staining of antigen-specific CD8+ T cells, proving its utility as a high-throughput screening tool for identifying previously unknown or 'orphan' TCRs. Importantly, when VLP-Open HLA was supplemented with costimulatory signals, it effectively functioned as an artificial antigen-presenting platform. This led to the induction of antigen-specific T cell activation and subsequent expansion, mimicking the physiological role of natural APCs. The platform's modular design also allows for the incorporation of various HLA allotypes and costimulatory molecules, enhancing its versatility for a wide range of experimental immunology applications. This offers a facile and standardized alternative to complex autologous antigen-presenting cell systems. > VLP-Open HLA nanoparticles displayed up to 60 peptide/HLA molecules, effectively staining antigen-specific CD8+ T cells and inducing their activation and expansion when combined with costimulation.