Basal lamina-associated heparan sulphate proteoglycan in the rat PNS: characterization and localization using monoclonal antibodies.

Cultured rat Schwann cells produce a basal lamina (BL)-associated heparan sulphate proteoglycan (HSPG). The HSPG has an apparent molecular weight of greater than 450 kD, is sensitive to both heparinase and heparitinase and contains a core protein of approximately 400 kD. Two independently derived monoclonal antibodies, B3 and C17, recognize this HSPG. Using B3 and C17, we found that this HSPG, or immunologically related material, is present in BLs throughout the body and in a small number of connective tissue sites without a formed BL. In the PNS it is present in BLs of Schwann cell-axon units, in synaptic and extrasynaptic portions of muscle fibre BL, and in the BLs of satellite cells that ensheath neurons in sympathetic and sensory ganglia. This HSPG is not detectable in the neuropil of the brain and spinal cord. Neurons, Schwann cells and fibroblasts cultured alone do not assemble a BL or accumulate immunocytochemically detectable amounts of this HSPG, but it is present in BLs assembled in myotube and in Schwann cell-neuron cultures. Thus, this HSPG is a component of most, if not all, BLs in the PNS.