[Determination of cell surface antigens on cryostat sections with monoclonal antibodies]

[Tissue expression of a gene potentially implicated in some diseases with retinal and renal involvement]

We have produced a monoclonal antibody (HA34) that specifically reveals the pigmented epithelium in the eye and the proximal convoluted tubules of the kidney, whatever the developmental stage. The results obtained with the kidney of other mammals suggest that the antigen is human specific. Its molecular weight is approximately 200 kDa. The epitope recognized by HA34 is always present on cell lines grown in vitro. This allowed us to use somatic cell interspecific hybrids to localize the gene implicated in the cytogenetic band 11q13, between microsatellites D11S1777 (AFMa046wa9) and D11S913 (AFM164zf12) in a 9 cM space. This region is involved in forms of retinitis pigmentosa, some of which can also include kidney abnormalities. We propose that this gene is possibly implicated in some of these diseases.

Developmental modifications of sheep kidney antigens

We have used monoclonal antibodies to study the changes in the expression of four kidney antigens during organogenesis in the sheep. Two of these antibodies, EE24.6 and EJ30.1, label intensely only the adult kidney, whereas the other two, EK17.1 and EJ15.1, bind to the extracellular matrix of the embryonic kidney. For EJ15.1, the staining of the extracellular matrix decreases temporarily during the second half of intrauterine life, a period during which a light staining appears in the mesangium. For the other, EK17.1, the extracellular matrix staining in the stroma gradually decreases as the embryo grows, while staining of the mesangium and the arterial intima becomes evident. With EK17.1, fibronectin is identified in the extracellular matrix of the embryonic kidney and intracellularly in the mesangial cells after these cells have colonized the glomerulus. The mesonephros staining seems to be the same as that of the metanephros. In the adult, extraglomerular vascular endothelial cells bind EK17.1, whereas intraglomerular endothelial cells do not express fibronectin, which suggests a functional difference between endothelial cells in these two localizations.