ANTIBODY SPECIFIC FOR EXTRA DOMAIN-B OF FIBRONECTIN DEMONSTRATES ELEVATED LEVELS OF BOTH EXTRA DOMAIN-B(-B(-) FIBRONECTIN IN OSTEOARTHRITICCANINE CARTILAGE() AND DOMAIN)

A fusion protein containing the alternately spliced Extra Domain B [ED -B(+)] sequence of canine fibronectin was expressed in E. coli and the purified protein was used to produce an antibody specific for the ED- B(+) segment. This antibody recognized canine cartilage fibronectin bu t not canine plasma or synovial fluid fibronectin. Using this antibody , it was determined that ED-B(+) fibronectin increased proportionally with the total fibronectin in osteoarthritic cartilage. From this resu lt, it was concluded that the chondrocyte is the source of much of the elevated fibronectin that appears in osteoarthritic cartilage.