Abstract
Purpose::
The development of lymph vessels (lymphangiogenesis) following corneal transplantation is known to be a risk factor for graft failure. We have previously shown a higher rejection rate for corneal transplantation in C57BL/6 mice than in BALB/c mice. We set out to determine the differences between C57BL/6 and BALB/c mouse corneas that might mediate the different rejection risk.
Methods::
Flat mounts were prepared from corneas of C57BL/6 and BALB/c mice, and observed by immunofluorescence for the presence of lymph vessels using LYVE-1 as a marker of lymphatic endothelial cells. The innate immune cells were detected using CD11b, CD40, as well as MHC-Class II as a co-stimulatory molecule-marker. Digital images of the flat mounts were taken using a spot image analysis system, and the area covered by lymphatic vessels was measured using NIH Image software. The number of immune cells was counted.
Results::
The area of lymph vessels in C57BL/6 corneas was significantly greater than in BALB/c corneas (p=0.03). Moreover, there were significantly more CD11b- (p<0.01) and CD40-, MHC-Class II- (+) cells in the C57BL/6 corneas than in BALB/c mouse corneas. In vitro analysis revealed that CD11b (+) antigen presenting cells express lymphatic endothelial markers and have the capacity to form tube-like structures.
Conclusions::
C57BL/6 mouse corneas have more endogenous CD11b (+) cells as well as more lymph vessels. We postulate that the endogenous lymphatic vessels, along with the pro-inflammatory CD11b (+) cells, account for the high risk of corneal graft rejection in C57BL/6 mice. CD11b (+) antigen presenting cells derived from bone marrow cell appear to play an important role in the induction of lymphangiogenesis.
Keywords: neovascularization • vascular cells • cornea: basic science