Which Cells Take Up mRNA Vaccine Nanoparticles and Release Viral Antigen?
Antigen-presenting cells (APCs), particularly dendritic cells and macrophages, are the primary immune cell types responsible for early uptake of lipid nanoparticles (LNPs) and subsequent mRNA translation to produce and present viral antigens. 1
Primary Cellular Targets
The most recent and highest quality evidence from non-human primate studies using PET imaging to track LNP trafficking demonstrates that:
- Antigen-presenting cells are identified as the primary immune cell type responsible for early LNP uptake and mRNA translation following intramuscular injection 1
- This includes both dendritic cells and macrophages as the key cellular targets 1
- These APCs take up LNPs at the injection site and subsequently migrate to draining lymph nodes, enabling localized immune priming 2
Mechanism of Action
The cellular uptake process follows this pattern:
- LNPs distribute through injected muscle tissue with rapid trafficking to draining lymph nodes (dLNs) 1
- APCs internalize the LNP-mRNA at the injection site, then migrate to lymph nodes where they present the translated antigen 2
- The LNP carrier itself acts as a powerful adjuvant, contributing significantly to the immunogenicity of the vaccine platform 3
Why Not the Other Options?
- Hepatocytes (Option A): While hepatocytes can take up LNPs (particularly with intravenous administration or GalNAc-conjugated formulations targeting liver), they are not the primary target for intramuscular mRNA vaccines 4
- Plasma cells (Option B): These are antibody-producing cells that develop after antigen presentation, not the initial cells that take up and present the antigen
- Dendritic cells (Option C): This is partially correct as dendritic cells are indeed among the primary APCs involved 1, 5
- Macrophages (Option D): Also partially correct as macrophages are among the primary APCs involved 1
Clinical Relevance
The answer encompasses both dendritic cells and macrophages as antigen-presenting cells, rather than a single cell type 1. The mechanism involves localized uptake at the injection site followed by migration to lymph nodes, which explains the efficacy and safety profile of mRNA vaccines with minimal systemic exposure 2.