IMMUNOHISTOCHEMICAL AND FUNCTIONAL-STUDIES ON RAT HIGH ENDOTHELIAL VENULES USING MONOCLONAL-ANTIBODIES

The distribution of high endothelial venules (HEVs) in various rat org ans has been investigated immunohistochemically using two monoclonal a ntibodies (MoAbs), REC16-11 and REC4-1. The staining patterns observed with REC16-11 and REC4-1 were compared with those obtained with the M oAb anti-rat ICAM-1, which is a cell adhesion molecule in HEVs. REC16- 11 reacted not only with HEVs but also with all vascular endothelial c ells (ECs) in the tissues examined. Electron-microscopy showed that RE C16-11 and REC4-1 reacted with the cell surface antigens of ECs and im munoblot analysis of rat splenic stromal preparations showed that REC4 -1 stained 42 kd and 60 kd bands. REC4-1 inhibited the binding of lymp hocyte to HEVs in the mucosa-associated lymphoid tissues (MALT), but h ad no effects on lymphocyte binding to HEVs in peripheral (non-mucosal ) lymph nodes. These findings suggested that the MoAb REC4-1 recognize d the associated antigen of the lymphocyte-HEV recognition system in M ALT.