An improved method for determination of serum adenosine deaminase activity and its clinical applications.

An improved method was devised for the estimation of serum adenosine deaminase activity. The principle of the method consists in measurement of a liberated ammonia by the action of the deaminase with a direct colorimetric determination of ammonia concentration [Okuda et al.]. The technique is relatively easy to estimate the serum enzyme activity and can be applied for routine clinical use. The serum adenosine deaminase activity assayed by this method was elevated in patients with hepatic disease and the others, such as auto-immune diseases, rheumatoid arthritis, malignant lymphoma, leukemia and multiple myeloma. The presented experiments were designed to clarify the origin of the elevated adenosine deaminase in serum. The heat stability and pH optimum were found to be essentially identical in sera from hepatic disease and the others. However, michaelis constant (Km) for adenosine and V max were higher in the sera from patients with hepatic diseases than those of the others. The isoelectrofocusing pattern of the serum enzyme was shown quite differnt between hepatic disease and the others. The results in the present investigation indicated that the enhanced serum adenosine deaminase activity and its isoenzyme pattern were very useful for clinical diagnosis. 203