[PubMed] [Google Scholar] 8. Our data indicate that PLGA-based killer MPs are capable of specifically depleting pathogenic T cells, which highlights their therapeutic potential for treating allograft rejection and autoimmune disorders. and environments due to the activity of cytotoxic T cells, which can lead to KAPC depletion or unwanted changes in cell-cell signaling [14, 15]. To circumvent the limitations associated with the cellular nature of KAPCs, killer artificial antigen-presenting cells (KaAPCs) Rabbit Polyclonal to BMX have been established by covalently coupling the HLA-A2-Ig OICR-9429 and anti-Fas IgM monoclonal antibody (mAb) onto cell-sized magnetic beads, and were capable of depleting antigen-specific T cells . We previously reported that latex bead-based KaAPCs could selectively deplete 60% alloreactive T cells and prolong alloskin survival for 6 days in a murine model without the loss of overall immune responsiveness . However, despite these promising results, the use of magnetic or latex beads as an acellular scaffold may evoke concerns regarding biosafety and organ toxicity Therefore, a biodegradable, non-toxic, and biocompatible platform should be further developed. Polylactic-co-glycolic acid (PLGA) is usually a biocompatible and biodegradable polymer that has been approved by the United States Food and Drug Administration (FDA) and has been widely used to deliver proteins, small molecule drugs, and other macromolecules in research and clinical settings [18, 19]. In this report, we investigated whether PLGA polyesters could covalently load antigen and monoclonal antibody (mAb) in order to generate killer microparticles (MPs) that could deplete antigen-specific T cells. PLGA MPs with a diameter of 4.0 m were fabricated on-site using a modified emulsion procedure and co-coupled by H-2Kb-Ig dimers together with anti-mouse Fas mAbs. Ovalbumin (OVA)257-264(SIINFEKL) is usually a well-known T cell epitope that is presented by H-2Kb molecules. Here, it was used as a guided missile to target the T cell receptor (TCR) of an OVA257-264-specific CD8+ T cell clone. Anti-mouse Fas mAb has been shown to induce apoptosis. The killer MPs could efficiently eliminate OVA257-264-specific CD8+ T cells from transgenic OT-1 mice in an antigen-specific manner and depletion of OVA257?264 antigen-specific CD8+ T cells by killer MPs Lymphocytes from OT-1 mice were co-cultured with OVA/killer-MPs, TRP2/killer-MPs, anti-Fas-MPs, or blank-MPs for 24 hours. The killing efficiency was then detected by flow cytometry. Annexin V/propidium iodide (PI) staining revealed a strong apoptotic effect in CD8+ T cells induced by OVA/killer-MPs at various ratios of MPs to lymphocytes. In contrast, only a slight apoptotic effect was observed in control co-cultures with TRP2/killer-MPs, anti-Fas-MPs, or blank-MPs, which OICR-9429 was comparable to the background death of CD8+ T cells cultured alone (Physique ?(Figure3A).3A). Representative flow cytometric dot plots for each group OICR-9429 are shown in Supplementary Physique 1A. The percentage of OVA257?264-specific CD8+ T cells in the co-cultures with OVA/killer-MPs was remarkably decreased compared to control co-cultures at all ratios of MPs to lymphocytes (Figure ?(Physique3B3B and ?and3C).3C). Notably, TRP2/killer-MPs as an unrelated antigenic epitope control did not lead to an obvious increase in apoptosis and reduction of OVA-specific CD8+ T cells, suggesting that this OVA/killer-MPs depleted CD8+ T cells in the co-cultures in an antigen-specific manner. Representative flow cytometric dot plots for H-2Kb/OVA-Ig dimer staining and anti-mouse V2 TCR staining in each group are shown in Supplementary Figures 1B and C, respectively. Furthermore, an incubation time-dependent increase in apoptosis and a reduction of OVA257?264-specific CD8+ T cells was observed in co-cultures with OVA/killer-MPs (Figure ?(Physique3D3D and ?and3E3E). Open in a separate window Physique 3 depletion of OVA257?264-specific CD8+T cells by OVA/killer-MPsA., B., C. OVA/killer-MPs exerted a strong apoptotic effect on CD8+ T cells and markedly decreased the percentage of OVA257?264-specific CD8+ T cells in an antigen-specific manner. Lymphocytes from OT-1 mice were seeded into 96-well round-bottom plates.