REVERSE TRANSCRIPTION-POLYMERASE CHAIN-REACTION AND IMMUNOHISTOCHEMICAL STUDY OF THE EXPRESSION OF FIBRONECTIN MESSENGER-RNA IN HUMAN SUBMANDIBULAR SALIVARY-GLAND

The alternative expression of fibronectin mRNA in submandibular saliva ry glands was analysed using three groups of polymerase chain reaction probes to amplify the cell-binding domain (CBD), and the extra domain (ED)A and ED-B exon regions in five normal human adults. The fibronec tin CBD region was fairly well expressed in the salivary gland while l ess than trace amounts of ED-A and ED-B exons were expressed. Immunohi stochemical staining with an antihuman plasma fibronectin monoclonal a ntibody, which recognized specifically the CBD region, demonstrated de finite positive cytoplasmic staining in the duct-cell area. On the oth er hand, an anticellular fibronectin ED-A-specific monoclonal antibody was very low positive in duct cells. The results suggest that salivar y fibronectin is synthesized in the submandibular salivary gland only. and does not include the ED-A segment. Furthermore, duct cells also p roduced fibronectin without ED-A. (C) 1998 Elsevier Science Ltd. All r ights reserved.