Abstract
Abstract: :
Purpose: Significant numbers of bone–marrow derived antigen presenting cells (APCs) have been recently identified in the corneal stroma of normal mice and pigs. These cells are a prominent focus of research for their potential in immunological tolerance and wound healing. This study demonstrates the presence and distribution of APCs in the canine corneal stroma. Methods: Normal canine corneas were harvested within 1 hour post–mortem, fixed in optimal cutting temperature media and stored at –20°C. Six µm sections were obtained through the frontal plane to create full–thickness representations of the axial anterior, paraxial, and peripheral posterior cornea. After acetone fixation, multilabel immunofluorescence was performed using primary antibodies against canine CD11b (monocyte marker), CD11c (dendritic cell marker), CD45 (common leukocyte antigen) and MHCII (mature APC marker). Controls were performed with these and isotype control antibodies on normal canine corneal and splenic tissue. Results: CD45–positive bone–marrow derived cells were present in increasing numbers from the axial anterior to the peripheral posterior cornea. CD11b–positive cells were identified in moderate numbers in the anterior and posterior stromal thirds. CD11c–positive and MHCII–positive cells were heavily distributed throughout the peripheral posterior cornea, but found rarely in the remaining corneal sections. Conclusions: Bone–marrow derived APCs reside in the normal canine cornea. Their increased density in the peripheral cornea parallels the corneal APC distribution in the mouse and pig. The presence of monocytic cells in the anterior and posterior stroma, as well as the increased density of mature APCs in the peripheral cornea, further resembles the APC distribution in mice. These cells may play a critical role in the induction of immunological tolerance and wound healing. Additonal and more interventional studies are indicated to determine the role of canine corneal APCs.
Keywords: antigen presentation/processing • cornea: stroma and keratocytes • transplantation