Transport of viral-size particulate matter after intravenous versus intralymphatic entry

Objective: Investigation of the transport of viral-size particles after int ravenous versus intralymphatic injection and the functional validity of lym phatico-venous communications. Methods: in the canine model, [Tc-99m] sulfur colloid particles (100-200 nm ) were injected into either the principal vein or into the main lymphatic c hannel exposed at the paw. Samples of blood and lymph were collected at the groin fi om the cannulated femoral vein and fr om a major lymphatic vessel . parameters including particle arrival time, concentration, flux, and accu mulation were determined for a 45-minute period using gamma collating. Results: After intralymphatic injection, particles arrived in the venous bl ood in an average of IC seconds. The mean arrival time of particles in the lymph after intravenous injection Ras 25.4 +/- 6.44 minutes. Intralymphatic injection increased lymph flow and enhanced particle transport. Concentrat ion values in the venous blood after intralymphatic injection and in lymph after intravenous injection were comparable. Flux values depended primarily on flow; conditions. Particle accumulation in the lymph after intravenous injection Tvas delayed, but continued to increase throughout the experiment . Conclusions: There are functional lymphatico-venous communications at the v ery peripheral level under physiological conditions, which allow rapid tran sport of viral-size particulate matter between the two pathways and may con tribute to the spl ead of viral infection.