IMMUNOCYTOCHEMICAL DEMONSTRATION OF PROSTAGLANDIN SYNTHASE (CYCLOOXYGENASE) IN THYMIC MACROPHAGES OF NORMAL AND CYCLOSPORINE-TREATED RATS

As revealed with ED1 and ED2 monoclonal antibodies, macrophages are sc attered throughout the thymic tissue. However, in contrast to the cort ex and medulla, in the cortico-medullary zone macrophages are large an d show strong reactivity with rabbit polyclonal antisera to cyclooxyge nase. Only few smaller cortical macrophages also show weaker presence of prostaglandin synthase. After cyclosporin treatment cortical macrop hages become strikingly similar to the macrophages of the cortico-medu llary zone of the normal thymus. Cortical macrophages become enlarged and develop the strong expression of prostaglandin synthase. Our resul ts show that a specific type of macrophages (with distinct histochemic al characteristics, enzyme profile and ultrastructural organization, w hich is strategically positioned within the thymic tissue - as we demo nstrated earlier) possesses the enzyme capacity required for prostagla ndin synthesis. After cyclosporin treatment, which interferes with the maturation of thymocytes, cortical macrophages thoroughly change and develop the strong prostaglandin synthase expression, similar to that of normal cortico-medullary zone macrophages.