Inhibition of Immune Cell Function by Adenosine: Biochemical Studies
Adenosine (Ado) has been shown to inhibit the cytolysis of tumor cells by specifically-sensitized mouse lymphocytes1. The mechanism of this immunosuppressive effect of Ado is of interest in view of the apparent causal relationship between Ado deaminase deficiency and severe combined immunodeficiency disease2. Thus far, Ado has been shown to cause two distinct biochemical effects in the cytolytic lymphocytes: (i) an elevation of adenosine 3′:5′-monophosphate (cAMP)1; and (ii) an elevation of S-adenosylhomocysteine (AdoHcy)3. Ado has little or no effect on the pool sizes of CTP, UTP, ATP or GTP in these cells1,4. Studies with other agents have shown that a selective elevation of either cAMP, as caused by prostaglandin E 1 5 , or AdoHcy, as caused by 3-deazaadenosine3, is sufficient to inhibit the cytolytic activity of these lymphocytes. The present studies were therefore undertaken in an attempt to discern the relative importance of cAMP and AdoHcy to this immunosuppressive action of Ado.
KeywordsCytolytic Activity Severe Combine Immunodeficiency Reversal Agent Immune Cell Function Hill Plot
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