NALT (nasal cavity-associated lymphoid tissue) in the rabbit

Due to its many advantages, interest in intranasal vaccination of domestic mammals and humans is currently increasing. Successful stimulation of the immune system by intranasal vaccines requires, however, the presence of lymphoid tissue in the nasal cavity. This nasal cavity-associated lymphoid tissue (NALT) has already been described in humans and many laboratory rodents, but data about rabbits are very scarce. For this purpose, histological sections of the nasal cavities of 10 female adult New Zealand White rabbits were examined for the presence of lymphoid tissue. Primary (I) and secondary (II) lymphoid follicles divided by interfollicular regions were mainly present at the bottom of the ventral nasal meatus and the nasopharyngeal meatus from 1 to 3.3 cm from the tip of the nose. In this region intraepithelial and lamina propria lymphocytes, and isolated lymphoid follicles (ILF's) were additionally seen at the dorsal and dorsolateral sides of the nasopharyngeal meatus and within the mucosae of the nasal conchae and the lateral nasal walls. Intraepithelial and lamina propria lymphocytes, and ILF's were, just like in humans, randomly distributed along the entire nasal mucosa. The rabbit NALT is more voluminous compared to rodents in which lymphoid tissue is only present at the bottom of the nasopharyngeal meatus. Since the relative volume of the rabbit nasal cavity is also similar to that of humans, the rabbit could be a valuable research model not only for animal but also for human intranasal vaccine development.