Single and coencapsulation of interferon-γ in biodegradable PLA microspheres for optimization of multicomponent vaccine delivery vehicles

Interferon-γ (IFN-γ) is a cytokine with potential for application in immunotherapy. Because of side effects following systemic administration, the use of such cytokines has been limited. The encapsulation of such agents in biodegradable microspheres is desirable, facilitating controlled release of drug from targetable devices. The combination of cytokines with antigens in a microsphere system may be of practicable value in providing a safe and novel class of carrier. Low-molecular-weight poly (L-lactide) (PLLA) was used for microsphere production by both single- and double-emulsion solvent evaporation techniques. The small microspheres produced in this study have the potential for mucosal delivery, desirable for vaccine delivery systems, being in the region of 1 μm in diameter with smooth spherical surfaces. The effect of inclusion of diluent proteins on the encapsulation efficiency and release characteristics of both types of preparations is discussed together with the mechanisms of release. The coencapsulation of IFN-γ with other proteins in such formulations requires investigation of the effect of each ingredient on the subsequent particle formation and release characteristics.