Figure 3.

Synthetic mast cell (MC) granules for targeted vaccination. (a) Scanning electron microscope micrograph of an activated rat peritoneal MC (natural) and a synthetic particle consisting of heparin and chitosan (synthetic). (b) Diagram demonstrating the modeling of synthetic particles after MC granules, where chitosan, made positively charged under acidic conditions, is substituted for MC proteases, enabling inflammatory mediators to be entrapped within a similar matrix structure containing heparin. (c) Lymph node (LN) sections after injection of saline, particles containing poly-l-lysine conjugated to the fluorochrome fluorescein isothiocyanate (PLL-FITC) (pFITC, green) or soluble PLL-FITC (sFITC, green). These LNs were isolated 45 minutes post-injection, sectioned, and stained for B cells (B220, red) and LN sinuses (Lyve-1, blue). (d) Day 21 geometric mean titers for total immunoglobulin (Ig) G after vaccination with haemagglutinin in combination with the designated adjuvants, with a boost at day 14. (e) Synthetic particles containing tumor necrosis factor (TNF) (pTNF) or the positive control, alum, increased the survival of mice challenged with influenza significantly over naive mice, antigenalone controls or soluble TNF (sTNF). (Adapted with permission from 89.)