Abstract
Abstract: :
Purpose: We have shown previously that dendritic antigen-presenting cells (APC) migrate out of transplanted corneas and into draining lymph nodes. These cells are CD11c+ but uniformly MHC class II-negative. However, following transplantation they express MHC class II antigens. In this series of experiments, we are examining the possibility that the migrating cells are functional APC. Methods: Corneal buttons were excised from BALB/c mice and incubated for 1, 3 and 6 days in culture. Non-adherent cells were isolated from the corneal explant cultures and evaluated for their allostimulatory capacity by mixing the corneal cells with responding allogeneic (C57BL/6) lymphocytes. Lymphocyte proliferation was measured 3 days later. We further characterized the non-adherent cultured corneal cells by flow cytometry. The cells were stained with a combination of antibodies against CD11c (dendritic cells), CD11b (macrophages), and MHC class II. Results: We found that cultured non-adherent cells derived from corneal explant cultures can stimulate alloreactive lymphocytes. The allostimulatory activity of the non-adherent cells increased with the length of time the corneal explants were incubated. By flow cytometry we detected dendritic cells (CD11c+) in the collected non-adherent corneal cells. Some (54%) of the CD11c+ cells were also CD11b+ suggesting a myeloid lineage. Furthermore, the CD11c+ cells increased their expression of MHC class II in culture, and this enhanced expression corresponded with an increase in their allostimulatory activity. Conclusion: These results indicate that resident corneal DC can potentially serve as functional APC after migrating from the cornea. Following transplantation, these DC are capable of expressing MHC class II antigens, migrating out of the corneal graft, and mediating allosensitization.
Keywords: 320 antigen presentation/processing • 413 flow cytometry • 607 transplantation