Peripheral Tissue Equivalent Module Compared to PBMC Assay

We have shown that the Peripheral Tissue Equivalent (PTE) module is significantly more sensitive than PBMC assays for certain immune stimulants such as double-stranded RNA, bacterial cell wall components, and bacterial DNA.

The PTE module provides valuable insight into the reactogenicity of immunotherapy formulations and the ability of immunopotentiators and adjuvants to induce innate- associated inflammatory responses.

We have determined that a multi-faceted analysis of inflammatory cytokines, DC viability/migration, and APC activation/maturation provides a comprehensive view of the innate potential of a particular test agent. We employed a variety of these techniques to examine the immunostimulatory potential of a panel of toll like receptor (TLR) ligands (poly(I:C), CpG 2006, LPS, and Gardiquimod) in the PTE. Since the culture of unfractionated PBMCs in the absence or presence of a test compound remains the mainstay approach for these types of evaluations, we also examined cytokine responses in parallel cultures of PBMCs from the same donors.

Taken together, the results of the Figure below demonstrate that the cytokine profiles induced by the TLR ligands are robust, but variable depending on the nature of the stimulus. In many cases, the TLR ligands failed to elicit detectable responses in the PBMC assay; in those instances where cytokines were elevated following treatment, the level of expression was 3-50-fold less than in the corresponding PTE culture. The results of this experiment can be taken to indicate that the PTE module is more sensitive than the conventional PBMC culture for evaluating TLR stimulation and suggest that enhanced TLR-induced cytokine production in the PTE module is attributable to a synergistic interaction between migrated immune cells and the HUVECs.

Bar Charts: TLR agonists induce cytokine production in the PTE module.