S-100 protein and neuron specific enolase immunoreactivity of normal, hyperplastic and neoplastic chondrocytes in relation to the composition of the extracellular matrix.

S-100 protein and neuron specific enolase (NSE) are no longer considered as specific cell markers indicating a neural origin. Since most of the cells displaying immunoreactivity for both markers also elaborate a stroma rich in chondroid or myxoid mucosubstances, we undertook the present study in order to clarify whether or not the positive immunoreaction is related to the composition of stromal glycosaminoglycans. The study was based on formalin fixed, paraffin embedded material comprising adult resting cartilage, reactive or hyperplastic cartilage, as well as benign and malignant chondroblastic tumors. Histochemical and immunohistochemical methods were applied on parallel sections with the following results: A positive immunoreactivity of the cartilage cells was always found to be related to the participation of chondroitine sulfate A and C in the stromal glycosaminoglycans. A NSE positive reaction was found in all cartilage cells displaying the characteristics of metabolically active cells. It is postulated that S-100 protein, as a calcium binding protein, might be involved in the cellular control mechanisms regulating the glycosaminoglycans-collagen interactions.