Objective: Investigation of the transport of viral-size particles after intravenous versus intralymphatic injection and the functional validity of lymphatico-venous communications.
Methods: In the canine model, [99mTc] sulfur colloid particles (100-200 nm) were injected into either the principal vein or into the main lymphatic channel exposed at the paw. Samples of blood and lymph were collected at the groin from the cannulated femoral vein and from a major lymphatic vessel. Parameters including particle arrival time, concentration, flux, and accumulation were determined for a 45-minute period using gamma counting.
Results: After intralymphatic injection, particles arrived in the venous blood in an average of 4 seconds. The mean arrival time of particles in the lymph after intravenous injection was 25.4 +/- 6.44 minutes. Intralymphatic injection increased lymph flow and enhanced particle transport. Concentration 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 was delayed, but continued to increase throughout the experiment.
Conclusions: There are functional lymphatico-venous communications at the very peripheral level under physiological conditions, which allow rapid transport of viral-size particulate matter between the two pathways and may contribute to the spread of viral infection.