Microsphere translocation and immunopotentiation in systemic tissues following intranasal administration

With a view to developing improved mucosal immunisation strategies, we have quantitatively investigated the uptake of fluorescent polystyrene carboxylate microspheres (1.1 μm diameter), using histology and fluorescence-activated cell sorting, following intranasal delivery to BALB/c mice. To qualify these biodistribution data, antigen specific memory and effector responses in the spleens of mice immunised nasally with Yersinia pestis V antigen loaded poly(lactide) (PLA) microspheres (1.5 μm diameter) were assessed at 4, 7 and 11 days. Irrespective of administration vehicle volume (10 or 50 μl), appreciable numbers of fluorescent microspheres were detected within nasal associated lymphoid tissues (NALT) and draining cervical lymph nodes. Nasal administration of the particles suspended in 50 μl volumes of phosphate-buffered saline (PBS) served to deposit the fluorescent microspheres throughout the respiratory tract ( P