ANTIBODIES SPECIFIC TO THE PLASMA-MEMBRANE OF RAT LUNG MICROVASCULAR ENDOTHELIUM

The highly purified, luminal domain of rat lung endothelial plasma mem branes was used as an immunogen to obtain monoclonal antibodies to the endothelial cell surface. The procedure was highly efficient, yieldin g antibodies which recognize three seemingly novel endothelial integra l membrane glycoproteins of molecular weights of 170, 114, and 95 kDa, respectively. By immunofluorescence, two of these antigens (170 and 9 5 kDa) appeared to be uniquely expressed by the lung microvascular end othelium. The third one, the 114-kDa polypeptide, was detected in the continuous endothelium of the lung, but also in the fenestrated endoth elia of pancreas, intestinal villi, and kidney peritubular capillaries . Partition in Triton X-100-soluble and -insoluble plasmalemmal compon ents suggests that two of these novel endothelial antigens (170 and 11 4 kDa) are specific for the plasma membrane proper only, while that of 95 kDa is present both in the caveolae and on the rest of the cell su rface. (C) 1997 Academic Press.