THE QUANTITATION OF THE ABSORPTION OF MICROPARTICLES INTO THE INTESTINAL LYMPH OF WISTAR RATS

The absorption of polystyrene microparticles across the intestine of rats was examined as a preliminary assessment of the efficacy of particles as vaccine delivery systems. The superior mesenteric lymph ducts of groups (n = 5) of Wistar rats were cannulated and the lymph analysed by flow cytometry. This allowed direct quantification of the numbers of particles absorbed. The 0.15 and 1.0 mu m particles were absorbed rapidly (after 5 min) in a temporally complex manner, with maximal absorption occurring 65 min after delivery, for both sizes of particles. Microparticles were absorbed in approximately equal numbers over 90 min (5.0 x 10(4) 0.15 mu m and 4.9 x 10(4) 1.0 mu m particles, respectively). The levels of particle absorption in the current study indicate that microparticulate delivery of vaccines may be a realistic possibility.