Adjuvant activity of linear aliphatic polyester and branched aliphatic oligoester microspheres

Abstract

Bovine serum albumin (BSA) was entrapped into microspheres prepared of terpolymer of DL-lactic acid, glycolic acid and mannitol (GA-M-DLLA), copolymer of DL-lactic acid and mannitol (M-DLLA) and two lactido-glycolide copolymers (DL-PLGA) by the solvent evaporation emulsion technique (w1/o/w2). Release of BSA from the microspheres into PBS, pH 7.2, or porcine blood serum was examined for 15 weeks and the effects of blood serum components on the degradation of the microspheres were recorded. Subcutaneous administration of a single dose of the microspheres containing 5 µg BSA to mice elicited biphasic immune responses irrespective of the type of the microspheres. Although the interval between the two phases was shorter in the mice treated with the terpolymer microspheres, adjuvant potencies, assessed in terms of antibody levels, were similar for all the four types of the microspheres.