Résumé : In this study, the possibility of producing highly antibody-loaded microparticles with sustained-release properties was evaluated. Polyclonal immunoglobulin G (IgG) was used as a model of antibody and its encapsulation into poly(lactide-co-glycolide) acid (PLGA) microparticles was performed by spray-drying a water-in-oil (w/o) emulsion. It was demonstrated that the use of the Resomer® RG505 PLGA allowed an IgG loading of 20% w/w with an encapsulation efficiency higher than 85%. The produced microparticles were characterized by a mean diameter lower than 10 µm. The burst effect was shown to reach a maximal value of 40%. IgG stability after encapsulation was also assessed. The use of this single PLGA provided a lag time of 3 months which dramatically slowed down the release rate after the initial release of the encapsulated IgG. Using blends of PLGA characterized by different inherent viscosities allowed decreasing the lag time and modulating the dissolution profile of the IgG from the spray-dried microparticles. Therefore, spray-drying a water-in-oil emulsion appeared to be a promising strategy to produce highly antibody-loaded microparticles characterized by sustained-release properties.