Lectin binding in bone matrix of adult rats with special reference to cement lines

The present study was designed to localize glycoconjugates recognized by four lectins (LFA, MPA, WGA, and ConA) in adult rat bone, histochemically and biochemically. LFA, a lectin recognizing sialic acid, stained intensely the cement lines of calvariae and the interface between cartilage and bone of mandibular condyles, which were also stained with WGA, and intermittently stained with ConA. The irregular bone surface of calvariae displayed intense positive reaction with LFA and WGA, while the osteoid of mandibular condyles and the smooth bone surface of calvariae were intensely stained with WGA and ConA, but weakly stained with LFA and MPA. MPA recognized osteoclasts. At the superficial layer of mandibular condyles, the bone matrix appeared positive as granules with LFA and as patches with MPA, WGA and ConA. Lectin blotting analysis of bone extracts revealed two LFA positive bands at molecular weights of 18 kDa and 45 kDa. The former was positive with WGA, ConA, and MPA, while the latter was positive with MPA. The result suggests that the LFA-binding glycoconjugates, possibly 18 kDa and/or 45 kDa sialoglycoconjugates, may contribute to cementing mechanism of cement lines and/or to the bone formation in remodeling process as well as in intramembranous and intracartilaginous osteogenesis.