Immunophenotyping of human dendriform cells from the conjunctival epithelium

Purpose. Conjunctival Langerhans cells are bone marrow-derived, antigen-presenting cells that play a major role in the immune response of the ocular surface, but they have as yet been little investigated, either functionally or phenotypically. This study was undertaken in impression cytology to provide an extended immunophenotype of human conjunctival dendriform cells. Methods. Immunostaining procedures were used to seek for the expression of the following 30 membrane antigens related to the immune system, using dendriform cells obtained in conjunctival specimens from 80 normal subjects and 105 with chronic conjunctivitis: class II antigens HLADR and DQ, CD1a (T6) and CD5, which usually mark Langerhans cells, macrophage markers CD14, CD36 and CD63, various lymphocyte antigens (CD2, CD4 and CD8), receptor to interleukin 2 (CD25), adhesion molecules and integrins (CD11a, CD11b, CD11c, CD18, CD29, CD41, CD61), the selectin CD62, ICAM-1 (CD54), ICAM-3 (CD50) and ELAM-1, CD45RO, related to activation of immune cells, and its ligand CD22, receptors to immunoglobulins (CD23 and CD32) and complement (CD21), transferrin receptor CD71, tryptase and vimentin, were thus investigated. Results. Conjunctival dendriform cells reliably expressed several antigens: class II antigens HLA DR and HLA DQ, CD1a, vimentin, CD11a and CD18 (LFA-1), CD14, CD22, CD36, CD45RO, ICAM-3 and CD63. Other markers were only occasionally found (CD4, CD11b, CD29, CD32 and CD54), and the remaining above antigens were not expressed. No relevant difference was found between normal and inflammatory specimens in the immunophenotype of dendriform cells. Conclusions. This study sheds light on the main antigen-presenting cells of the ocular surface. The conjunctival cells share common immunophenotypic features with those from skin or mucosae, but our results showed some discrepancies, probably related to the specific immune status of the ocular structures.