Parenteral Delivery of Peptides and Proteins - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 568

T-lymphocyte activation efficiency ( Fig. 11.12 ) [350,351] . To increase efficiency of the
particulate system as an adjuvant and carrier for vaccines, immunostimulatory mol-
ecules, such as toll like receptor (TLR)-ligands, are being investigated [349] .
Apart from biodegradation kinetics, the mode and rate of presentation of antigen,
toxicity, tissue compatibility, antigen polymer compatibility, and antigen stability are
critical for the selection of appropriate polymer and method of preparation. Polymer
compatibility can be increased by modifying the internal pH of micro- and nanopar-
ticles and accelerating swelling with the help of buffer salts and other protein stabiliz-
ers. Precaution must be taken to preserve the antigen from various formulation and
process parameters like shearing, temperature, pH, lyophilization, moisture, hydro-
philic-hydrophobc interface, salts, and organic solvents. Table 11.10 shows the appli-
cations of polymeric particulate system as an adjuvant in vaccine delivery system.

Ovalbumin

Encapsulated
ovalbumin

Polyurethane with acetal
moities (acid labile)

Macrophage

Particle
phagocytosis

Fully degraded
polymer

Dendritic cell

T-cell

T-cell

T-cell

Ovalbumin presentation
to T-cells

Figure 11.12 Cytotoxic T-lymphocyte activation by acid-degradable particles.