The effect of size on uptake of orally administered latex microparticles in the small intestine and transport to mesenteric lymph nodes.

PURPOSE

The present study examines the relationship between size and particle transit across the mucosal barrier of the gastrointestinal tract to other sites of the body. The extent of particle uptake with increasing size, the tissue distribution and cut-off points for 2-20 microns particles is investigated.

METHODS

An established fluorescent latex particle-young adult rat model is used and particle numbers in small intestine and mesenteric lymph nodes, 0.5 h post administration, counted by fluorescence microscopy in bulk tissue specimens and cryosections.

RESULTS

Bulk tissue analysis provides evidence for the presence of particles of all sizes in the Peyer's patch regions, but only for 2 microns particles in the nodal tissues. Microscopy establishes uptake of both 2 and 6 microns particles in most intestinal and nodal tissue sites and compartments. By contrast, uptake of the larger particles is much reduced.

CONCLUSIONS

Although more of the smaller (2 microns) particles are taken up, particularly by epithelial tissues, the 6 microns size appears more efficient in terms of volume translocated to lymph nodes. This could have implications in the therapeutic use of particles for drug and vaccine delivery and for radiation safety.