Biodegradable microspheres II: Immune response to a heterologous and an autologous protein entrapped in polyacryl starch microparticles.

Human serum albumin (HSA) and mouse serum albumin were entrapped in biodegradable microparticles of polyacrylstarch. When HSA entrapped in microparticles was injected i.v. in Balb/c mice a dose-dependent immune response was elicited. No detectable response was obtained when mouse serum albumin entrapped in microparticles was given to the mice. Neither was any response detected when free HSA or free HSA in combination with empty microparticles were injected, as measured by indirect plaque-forming cells in the spleen and serum antibody titers. The immune response to entrapped HSA had a long duration and was mainly T-cell-dependent as athymic nude mice (Nu/Nu) only generated a weak immune response upon injection of the particle entrapped antigen.