Immune Response to the Introduction of Fibrillogenic β2-Microglobulin Protein Conjugated with Different Types of Polymer Particles

Abstract

The effect of the composition and size of polymeric particles on the immunogenicity of the fibrillogenic β2-microglobulin protein immobilized on their surface was studied. For this purpose, nanoparticles (NP) based on a copolymer of L-glutamic acid and L-phenylalanine (P(Glu-co-Phe)) and a block copolymer of poly(ethylene glycol) with poly(lactic acid) (PEG-b-PLA) as well as microparticles (MP) based on poly(lactic acid) (PLA) were selected. α-L-amino acid copolymer-based nanoparticles were prepared by gradient phase inversion, and PEG-b-PLA-based nanoparticles by nanoprecipitation. Double emulsion method was used to form polymeric microparticles based on PLA. Recombinant chimeric model protein beta-2-microglobulin-green fluorescent protein (β2M-sfGFP) was used to covalently modify all types of polymeric particles followed by immunization of four groups of laboratory animals equal in number. An enzyme immunoassay method was used to evaluate the humoral immune response. In three experimental groups, mice were immunized using poly(amino acid)-based nanoparticles (NP-PAA) and PEG-b-PMC (NP-PLA) as well as PLA microparticles containing immobilized β2M-sfGFP on the surface. The control group was immunized using a physical mixture of PEG-b-PLA nanoparticles and free β2M-sfGFP. The highest level of antibodies to sfGFP in blood serum was found when mice were immunized with a mixture of protein and nanoparticles. When mice were immunized with β2M-sfGFP-modified nanoparticles, the amount of antibodies to sfGFP was statistically significantly lower (p0.001) compared to the control group. However, the groups immunized with nanoparticles of similar size but different composition conjugated to the model proteins did not differ significantly among themselves. It was also found that the size of the particles affects the immunogenicity of the associated protein. A similar pattern of relative antibody content in the sera of mice was maintained at all steps of immunization.