Effective antigen delivery via dual entrapment in erythrocytes and autologous plasma beads

Fibrin-based polymeric systems have now emerged as efficient carriers of drugs, growth factors, genes, and cells. Earlier, we have reported fibrin-based plasma beads (PB), prepared from clotted whole plasma, as an efficient system for the controlled release of entrapped therapeutics. In the present study, we investigate the dual entrapment in erythrocytes and PB, as potential particulate antigen delivery system in rabbit and mice, with yeast invertase as the model antigen. Preparations used for immunisation include- invertase entrapped in erythrocytes, the same further entrapped in PB, and crosslinked with glutaraldehyde. While route of administration of the antigen only moderately affected the antibody titres, strategies slowing its release from PB increased the antibody titres remarkably, especially after a booster. Entrapment of erythrocytes entrapped antigen in the PB and further crosslinking with glutaraldehyde also resulted in significant alterations of IgG1/IgG2a ratio, indicating a shift towards humoral response. The elicited immune response was more marked in rabbits as compared to that in mice. Considering the well-known toxicity of the adjuvant, comparable antibody titres induced by the erythrocyte-plasma bead system was encouraging in the induction of humoral immunity.