Abstract
The use of microparticles, small beads of material 1 mm to 1000 mm, has been proposed as a potential delivery system for drugs or vaccines. Encapsulating the drug or antigen to be delivered within microparticles prevents premature degradation, allows sustained release, and enables targeting of specific cells and tissues. In addition, by targeting delivery to and stimulating antigen presenting immune cells (such as macrophages) microparticles have the potential to act as adjuvants, enhancing the immune response against a delivered antigen. Past studies have examined microparticles manufactured from a variety of materials. Because of unique qualities allowing relatively easy, inexpensive production without the use of protein degrading organic solvents traditionally required in the manufacture of microparticles, this study examined Aloe pectin as a microparticle source. To begin ascertaining Aloe pectin microparticles as a potential delivery system, this study examined their interactions with macrophages. Culturing the macrophage cell line RAW 264.7 with Aloe pectin microparticles demonstrated that they are quickly and easily phagocytosed without persisting in the cells over 24 hours. Treating macrophages with Aloe pectin microparticles also stimulated the cells to produce NO in concentrations produced by cells treated with LPS, an established activator of macrophages. Furthermore, western blot analysis of the cell lysate from macrophages cultured with Aloe pectin microparticles demonstrated the presence of iNOS, indicating cell activation. To explore the possibility of a pectin receptor on the macrophages, the cells were solublized and mixed with Aloe pectin microparticles over time allowing binding between the microparticles and the cell proteins to occur. The samples were washed to remove any unbound proteins from the microparticles. Analysis by gel electrophoresis revealed three proteins bound to the Aloe pectin microparticles. This study demonstrates that Aloe pectin microparticles are phagocytosed by and activate macrophages, reinforcing their potential as an antigen delivery vehicle.
Rainey, Robert Craig (2002). The interaction of Aloe pectin microparticles with macrophages. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -R343.