[Further studies on modification of phenoloxidase by effectors]

With the aid of the histochemical phenoloxidase (PO) assay, 12 substances were tested. On the one side they can act as substrates or as inhibitors of phenoloxidase and on the other side as immunogenic or immunosuppressive compounds. In particular the following substances were investigated: o-cresol, Levamisol, prednisolonebisuccinate, Bleocin, siliciumdioxide, 4-methylbrenzcatechol, +-catechine, thiomersal, D-penicillamine, hydrochinonemonomethylether, hydrochinonemonoethylether, and hydrochinonemonobenzylether. No changes in the phenoloxidase activity and in the morphological behaviour of the cells could be detected using Levamisol, prednisolonebisuccinate, siliciumdioxide, and Bleomycin, indicating an immunogenic stimulation or immunosuppressive effect. 4-methylbrenzcatechol is probably transformed into a soluble reaction product by phenoloxidase. It could not clearly demonstrated by the histochemical method, if this substance is used as a true substrate. +-catechine, thiomersal, and D-penicillamine cause strong to complete enzyme inhibition of the phenoloxidase containing cells (POC), which are located in the spleen and gut of the white rat. Hydrochinonemonoethylether, hydrochinonemethylether, and hydrochinonemonobenzylether cause an increased pigment fermentation, but they are not used as substrates for the PO.