Abstract
Abstract: :
Purpose: To explore and modulate the lymphatic drainage system and to determine its influence on corneal graft survival in mice. Methods:Two microliters of 99mTC colloidal albumin (Nanocoll®) were injected into the anterior chamber of the left eye of 6 BALB/c mice. Four groups of 6 mice received subconjunctival Nanocoll® injections. The submandibular lymph nodes were removed either on the left 7 or 21 days prior to Nanocoll® injection or bilaterally 7 days beforehand. Twenty-four hours later blood was obtained from each animal by heart puncture. The right and left eyes, the right and left submandibular lymph nodes and the spleen and liver were removed. The probes were weighed, and radioactivity was measured by a well-type NaI(TI) gamma scintillation detector (Baird Atomic). A standard probe was measured for each animal to calculate the radioactivity per mg of tissue or ml of blood corresponding to 106 counts per minute of the injected suspension. Four further groups of 6 BALB/c mice each received an orthotopic corneal transplant from C3H mice. Three of these groups underwent preoperative submandibular lymphadenectomy as in the above-mentioned tracer experiments. Results:Radioactivity was detected as follows: 90.7% in the liver, 7.5% in the spleen and 1.1% in the left lymph node after intracameral Nanocoll injection; 25.2% in the liver, 1.5% in the spleen and 71.6% in the regional lymph node after subconjunctival injection. The count rate/min/mg of tissue was about five times higher in the left than in the right submandibular lymph node after intracameral injection (p<0.01). However, subconjunctival injection increased this factor to 200. Removal of the left submandibular lymph node dramatically increased the count rate in the right submandibular lymph node (p<0.01). Bilateral lymphadenectomy increased the count rate in the blood (p<0.01) and spleen (p0.05). In three animals of group 4 the transplant was clear on day 35. Conclusion:Our data confirm functional lymphatic drainage via the uveoscleral pathway and conjunctiva in mice. The more intensive lymphoid connection between the outer eye and the regional lymph node could potentially be manipulated to improve graft survival.
Keywords: 324 aqueous • 607 transplantation • 433 immune tolerance/privilege