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

The absorption of polystyrene microparticles across the intestine of r ats was examined as a preliminary assessment of the efficacy of partic les as vaccine delivery systems. The superior mesenteric lymph ducts o f 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 r apidly (after 5 min) in a temporally complex manner, with maximal abso rption occurring 65 min after delivery, for both sizes of particles. M icroparticles 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, respective ly). The levels of particle absorption in the current study indicate t hat microparticulate delivery of vaccines may be a realistic possibili ty.