KERATAN SULFATE AND DERMATAN SULFATE PROTEOGLYCANS ASSOCIATE WITH TYPE-VI COLLAGEN IN FETAL RABBIT CORNEA

Keratan sulfate proteoglycan (KSPG) and dermatan sulfate proteoglycan (DSPG) are associated with collagen fibrils in adult rabbit cornea. Be cause certain cytochemical data suggested that proteoglycans are assoc iated with type VI collagen in the fetal rabbit cornea, we developed p olyclonal antibodies specific to the core proteins of rabbit corneal K SPG (lumican and/or fibromodulin) and DSPG (decorin and/or biglycan) a nd used the antibodies as immunocytochemical probes to determine prote oglycan ultrastructural location. Immunogold particles were associated with Type VI collagen filaments but not with collagen fibrils in feta l and neonate rabbit cornea. Association of corneal KSPG and DSPG with Type VI collagen was immunocytochemically confirmed with monoclonal a ntibodies to low-sulfated keratan sulfate glycosaminoglycan (GAG) and chondroitin-4-sulfate GAG of DSPG. The monospecificity of the polyclon al and monoclonal antibodies and exclusive binding of antibodies to Ty pe VI collagen filaments, together with previous chemical identificati on of low-sulfated KSPG and DSPG in developing rabbit cornea, support our contention that corneal proteoglycans in developing rabbit cornea are associated with Type VI collagen.