Release of a Model Antigen from Pellets prepared by Compression of Quil A-Cholesterol-Phospholipid PowderMixtures forming ISCOMs upon Hydration

摘要

Quil A-cholesterol-phospholipid powder mixturescontaining the model antigen PE-FITC-OVA wereprepared by physical mixing or by freeze-drying ofaqueous dispersions of these components in ratios thatallow the formation of ISCOMs. Lipid powder mixtureswere compressed to form small pellets. Release of PEFITC-OVA from the compressed pellets was investigated.Negative staining transmission electron microscopy (TEM)was used to characterize the type of colloids formed uponhydration of compressed pellets. PE-FITC-OVA wasreleased from the pellets in a sustained manner. Pelletsprepared by compression of freeze-dried powders releasedPE-FITC-OVA slower than those prepared from physicallymixed powders. TEM investigations revealed that theantigen was released in form of ISCOMs especially frompellets prepared by compression of freeze-dried powders.The addition of excess cholesterol to lipid powders sloweddown release of antigen. The results obtained in this studyare important in formulating solid Quil A-lipid mixtures assustained release particulate delivery systems for antigen.