APC Migration and antigen uptake is increased by the TLR2 ligand Neisserial Porin PorB (53.4)

Abstract

TLR ligands play an essential role in identifying threats to the innate immune system, which can then activate the adaptive arm. Our lab has worked with the N. meningitidis outer membrane protein Porin B (PorB), a TLR2 ligand, and shown that it increases the adaptive immune response as measured by antibody production and T cell activity. In examining the adjuvant activity of PorB we now investigate the ability of PorB to increase APC antigen uptake and migration to effector draining lymph nodes. Using an in vitro model with a fluor-linked antigen we show that PorB increases the quantity of the model antigen ovalbumin taken up by the APC in a rate dependent manner. We are in the process of characterizing the intracellular compartmentalization of the processed antigen by fluorescent microscopy of BMDM. In vivo experiments were conducted using a hock injection model and tracking the movement of the antigen through its fluorescent tag. Draining lymph nodes were examined through flow cytometry and immunofluorescence of frozen node sections. Using the latter technique, we are studying changes to lymph node morphology with the inclusion of the TLR ligand. Confirming the in vitro results, the addition of PorB to a vaccine injection increases the degree of APC migration to draining lymph nodes and the carriage of the antigen by these cells. With these results we have identified characteristics of the TLR2 ligand PorB that may account for some of its efficacy as a vaccine adjuvant.