PDPN and rheumatoid arthritis: In contrast, we detected 1325:01B09 binding to multiple cells from the dense layer of CD55 and podoplanin-(PDPN)-positive fibroblasts in the synovial membrane of two out of the four tested inflamed RA synovial tissues, whereas virtually no binding of the clone 1325:04C03 was observed in the CD55 and/or PDPN-positive areas (figure 6B).