Qualitative and quantitative differences between Burkitt lymphoma and lymphoblastoid cell lines in the expression of membrane ecto‐nucleotidases and in the response to agonists of the A2‐type adenosine receptor

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Abstract
The activity of ecto‐nucleotidases has been determined on intact cells from Burkitt lymphoma (BL) and lymphoblastoid cell lines established in vitro (LCLs). BL cells never express ecto‐5′‐nudeotidase (5′‐N) and exhibit only low levels of ecto‐ATPase activity, whereas LCL‐cells usually express both enzymes to varying degrees. There is a certain correlation (r = 0.75) between 5′‐N and ecto‐ATPase. When cAMP formation in response to agonists of the A2‐typc (stimulating) adenosine receptor is measured in the same cell lines there is no correlation with the expression of ecto‐nucleotidases. Within pairs of BL and LCL cell lines derived from the same donor, 5′‐N inverse relationship between ecto‐nucleotidases and the response to the adenosine receptor agonist N‐ethyl‐car‐boxamido‐adenosine (NECA) is observed. BL cells show a good response to NECA, whereas this is low or absent in LCL cells. Treatment of cells which exhibit both S′‐N and the adenosine receptor with specific polyclonal or monoclonal antibodies against the enzyme does not impair the function of the receptor. Antisera against peptides of the membrane antigen BNLF I‐MA, coded by the EBV‐genome, do not co‐precipitate 5′‐N out of detergent extracts of LCL‐cells. In both cases 5′‐N cannot be closely associated with other membrane components. The differences between BL and LCL cells in ecto‐nucleotidases and the adenosine receptor appear to be fairly stable phenotypical markers, independent of other parameters and suitable for use in distinguishing these cells in all populations.