Abstract
Abstract: :
Purpose:Several studies have demonstrated the up-regulation of B7.2 before B7-1 on antigen presenting cells (APCs), including B cells and dendritic cells, after in vitro culture. Few studies have examined the expression of these cell surface molecules during the course of an immune response in vivo. We investigated the kinetics of expression of B7.1 and B7.2, as well as which cell in the iris/ciliary body ICB) expressed these molecules, during the course of clinical disease. Methods:EAAU was generated in Lewis rats by immunization with melanin-associated antigen. Eyes were collected at different stages of disease, the anterior segment removed and digested enzymaticly to form single cell suspensions. The cells were double labeled with FITC-conjugated CD3, MHC II or ED2 antibodies and purified anti B7.1 or B7.2 antibodies followed by PE-conjugated anti-mouse IgG. Samples were analyzed by flow cytometry. Results:B7.1 and B7.2 are minimally expressed in the normal eye. B7.2, but not B7.1, was detected in the eye prior to the onset of inflammation - on day 8 (i.e. at the time of cellular infiltration on light microscopy and before the onset of clinical disease). However, both B7.1 and B7.2 are markedly augmented during the acute phase of the disease. Interestingly, B7.1 and B7.2 positive cells were reduced during remission, although inflammatory infiltrates were still present in the ICB. We analyzed individual cell subsets, including infiltrated T cells, MHC class II positive cells and resident macrophages in the eye at the onset of disease. We found that MHC II positive cells were significantly increased from normal (2% to 37%) and expressed B7.1 and B7.2 highly. ED2 positive cells, i.e. resident macrophages, were only slightly increased compared to the resting state (i.e. 1.5%) and expressed B7.1 and B7.2 at the onset of disease as well. Conclusion:B7.2 is expressed before B7.1 in the eye during the onset of uveits. However, the evolution of intraocular inflammation require both B7.1 and B7.2. Cells expressing MHC class II molecules are significantly enhanced during the onset of disease and are probably efficient antigen presenting cells since they express highly B7 molecules.
Keywords: 320 antigen presentation/processing • 318 anterior segment • 327 autoimmune disease