Adenylate kinase as a marker for platelet lysis

The level of extracellular lactate dehydrogenase (LDH) activity is often used as an indicator for the leakage of cytosolic platelet contents. The objective of this investigation was to study the possibility of using a different enzyme, adenylate kinase (AK), as a substitute for LDH. A bioluminescent assay was used, and three different platelet storage containers were studied. In a comparative study of AK and LDH activities during platelet storage, similar results were obtained, but some differences were also observed. Because more AK (in percentages) than LDH is contained in platelets, the initial levels of AK are lower than those of LDH. The release of AK activity from damaged platelets is delayed or is somewhat lower than that of LDH. The amount of AK activity released per platelet is correlated with the volume of the platelet units. A smaller volume entails increased AK activity. This observation applies to all storage conditions investigated, and the results in one of the containers indicate that this is also true for LDH. The results of the investigation demonstrate that similar information is obtained with LDH and AK. AK can be used as an alternative to LDH for studies of lytic processes during platelet storage.