Visualization of Inoculated Eyedrop Draining Passages and Identification of Eyedrop Draining Lymphnodes and Antigen Presenting Cells in Eyedrop Vaccination

In our previous study, IN vaccination showed significantly stronger level of immune induction compared to the eyedrop vaccination. However, the eyedrop vaccination activates both tear-associated lymphoid tissues (TALT) and nasal-associated lymphoid tissues (NALT). Moreover, there has been only T cell proliferation assay for the detection of draining lymphnodes of eyedrop vaccination. Therefore, the clarification of the draining passageway of eyedrop vaccination and the comparison of the draining lymphnodes between those two different entry sites are needed.

In here, we firstly visualized the route of drainage of the eyedrop vaccine and showed that the draining lymphnodes for eyedrop vaccination are different from those of intranasal vaccination in mice. The visualizing materials administered by eyedrop drained out through tear duct and nasal cavity. After the FITC solution was injected by eyedrop, superficial parotid lymphnodes (SPLN), mandibular lymphnodes (MdLN), inguinal lymphnodes (InLN) and spleen (SPL) were all FITC positive. However, 2 days after FITC-beads inoculation by eyedrop, superficial parotid lymphnodes (SPLN) were bead positive only in the presence of poly(I:C) and little mandibular lymphnodes (MdLN) were bead positive. In contrast, intranasally administered beads were detected in both SPLN and MdLN. Among FITC-beads positive cells in SPLN, they were CD11c⁺CD86⁺ or F4/80⁺. These results suggest that inoculated eyedrop vaccine antigens are captured by CD11c+ DCs and possibly participate in the presentation of the antigens to T cells in SPLN, rarely in MdLN, which a pattern is distinguished from that of IN vaccination.