Determining Whether Agonist Density or Agonist Number Is More Important for Immune Activation via Micoparticle Based Assay

Front Immunol. 2020 Apr 9:11:642. doi: 10.3389/fimmu.2020.00642. eCollection 2020.

Abstract

It is unknown if surface bound toll-like-receptor (TLR) agonists activate cells via density or total molecular number. To answer this question, we developed a TLR agonist surface conjugated polystyrene microparticle (MP) system. Using a library of MPs with varying TLR agonist density and number, we simultaneously observed innate immune cell MP uptake and TNFα expression using ImageStream flow cytometry on a cell by cell basis. The data shows that total TLR number and not density drives cellular activation with a threshold of approximately 105-106 TLR agonists. We believe that this information will be crucial for the design of particulate vaccine formulations.

Keywords: In vitro quantification; activation threshold; innate immunity; microparticle; toll-like-receptor.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Adhesion
  • Cells, Cultured
  • Humans
  • Immunity, Innate
  • Immunoassay / methods*
  • Lipid A / analogs & derivatives
  • Lipid A / chemistry
  • Lipid A / metabolism
  • Lymphocytes / metabolism*
  • Microplastics / chemistry
  • Oligopeptides / chemistry
  • Oligopeptides / metabolism
  • Polystyrenes / chemistry
  • Toll-Like Receptor 2 / agonists*
  • Toll-Like Receptor 2 / chemistry
  • Toll-Like Receptor 2 / metabolism
  • Toll-Like Receptor 4 / agonists*
  • Toll-Like Receptor 9 / agonists
  • Toll-Like Receptor 9 / chemistry
  • Toll-Like Receptor 9 / metabolism
  • Toll-Like Receptors / agonists*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Lipid A
  • Microplastics
  • Oligopeptides
  • Polystyrenes
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptor 9
  • Toll-Like Receptors
  • Tumor Necrosis Factor-alpha
  • PAM2-CSK4
  • monophosphoryl lipid A