Abstract
Purpose: :
Networks of major histocompatibility complex (MHC) class II– positive cells in the human iris have been identified previously by immunohistochemistry. To further determine the phenotype and distribution of antigen presenting cells in the human iris, we chose several dendritic cell (DC) and macrophage markers that have been investigated in studies on other tissues, but to our knowledge not reported in the human iris.
Methods: :
Immunohistochemistry following a standard protocol was performed on frozen sections of iris from human donors with monoclonal antibodies to human DEC 205, CD11c and CD11b. Anti–HLA–DR was subsequently applied to determine the presence of MHC class II surface molecules on CD11c and CD11b positive cells. Tonsil was used as a positive control tissue, and isotype–matched antibodies were used as negative controls. Following specific staining, the frequency and distribution of the positive cells were documented.
Results: :
A rich network of MHC class II–positive cells, mostly of dendriform appearance, was seen. Only a small percentage of these cells also stained for CD11c. Staining for CD11b could not be obtained reliably. All iris tissues stained repeatedly negative for DEC 205.
Conclusions: :
For the first time, immunohistochemical techniques have identified CD11c + dendriform cells in the human iris. Based on murine studies, iris dendritic cells have unique functional and migratory behaviors. Characterizing the phenotype of DCs is an essential step in clarifying this function.
Keywords: antigen presentation/processing • microscopy: light/fluorescence/immunohistochemistry • iris