Abstract
ADA is found in the sera of all mammals except the horse and the concentration of serum adenosine (Ado)is correspondingly low (<1 uM). In this study we examine the possible origin of extracellular ADA. Cells from freshly isolated mouse spleen were incu bated in phosphate buffered saline containing 5 mM glucose and 0.1% bovine serum albumin(BSA) for up to 2 hrs; S49 thymoma cells were incubated in serum-free Dulbecco's modified Eagle's medium containing 0.1% BSA for up to 24 hrs. Cells were rapidly separated from incubation medium by centrifugation through a layer of silicone oil. Intracellular and extracellular ADA was measured by determining the rate of conversion of 3H Ado(1 uM,6 uCi/ml) to inosine+hypoxanthine. To account for extracellular ADA due to cell lysis, intracellular and extracellular lactate dehydrogenase was also measured. On several occasions S49 cells which had been incubated for 20-23 hrs were washed, resuspended and incubated for further time intervals. The appearance of ADA activity in the extracellular medium was time and cell concentration dependent and could not be accounted for by dead or leaky cells. Between 7-10% of the initial intracellular activity was secreted during an 8 hr period. We conclude that lymphocytes secrete ADA. Supported by NSF PCM 77-25434 and ONR 14-82-K0283.
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Strauss, P. MURINE LYMPHOCYTES AND LYMPHOCYTE LINES SECRETE ADENOSINE DEAMINASE(ADA): 207. Pediatr Res 19, 778 (1985). https://doi.org/10.1203/00006450-198507000-00227
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DOI: https://doi.org/10.1203/00006450-198507000-00227