Samenvatting

Owing to the non-toxic, nonimmunogenic effects and high affinity to specific molecules, some single-stranded oligonucleotides, namely aptamers, can be exploited in biochemical applications to deliver bioactive elements and interact with the desired targets. Among many
identified aptamers, D#7 was utilized to transport antigens to dendritic cells (DCs) by binding selectively to this antigen-presenting cell. After internalization, it lead to the recruitment of further immune responses including activating T cells. However, the pathway how D#7 was processed inside DCs remained unknown. Therefore, this research examined the colocalization of labelled D#7 with ATTO 647N fluorophore and its conjugate to OT-I, a sequence of ovalbumin protein (OVA) consisting of specific binding sequence to Major Histocompatibility Complex (MHC) molecules class I. The positioning of the aptamers over time was investigated in early endosomes, late endosomes and lysosomes at multiple timepoints. Interestingly, D#7 colocalized in three organelles at the same rate at 10 minutes. At 1 hour, the colocalization was more significant in early endosomes. Meanwhile, the conjugate (D#7-OT-I) located predominantly in early endosomes at 10 minutes of internalization. After degradation, the remaining signals shifted mainly to late endosomes at 1 hour. The difference between D#7 and D#7-OT-I confirmed the influence of the antigen on the movements of the aptamers inside DCs. This result highlights the potential of D#7 as a transporter to escort the antigens of interest to DCs selectively, hence, leading to the activation of either cytotoxic T cells or T helper cells.