Acid phosphatase activity of human gingival fibroblasts measured using a simultaneous coupling semi-permeable membrane technique

Summary Acid phosphatase activity has been measured in cultured human gingival fibroblasts using a validated histochemical simultaneous coupling semi-permeable membrane technique. The histochemical reaction was linear over a three hour incubation period and had a pH optimum of 5.0. The activity was not increased by prior exposure to hypotonic acetate buffer and was inhibited by fluoride and molybdate but not by formaldehyde. These results indicate that the semi-permeable membrane technique described may be used for observing and measuring acid phosphatase activity in cultured fibroblasts. From results obtained using inhibitors, it appears that in these cells most of the acid phosphatase observed is lysosomal. The absence of any activation of activity following pre-incubation with hypotonic buffer indicates that the method is not suitable for monitoring lysosomal membrane function.