Evidence against functional adenosine receptors on murine lymphocytes

The effects of adenosine, 2-chloroadenosine (2Cl Ado) and N6-phenylisopropyladenosine (PIA) were examined on peripheral blood and splenic lymphocytes from mice. Lectin-stimulated DNA synthesis was antagonized by adenosine and 2Cl Ado at high concentrations. Lower concentrations of all three nucleosides produced an enhancement of lectin-stimulated thymidine uptake in splenic lymphocytes. Peripheral blood lymphocytes were found to exhibit only inhibitions of mitogenic stimulation suggesting a difference in response to nucleoside exposure between spleen and peripherally circulating cells. The synthesis of antibody to sheep red blood cells was inhibited in a non-cytotoxic manner by 2Cl Ado and PIA while adenosine was without effects. The receptor antagonist 8-phenyltheophylline was found to block nucleoside increases in thymidine uptake and low concentrations of 2Cl Ado with regard to antibody production. The effects of high concentrations of 2Cl Ado or PIA on humoral responses were not antagonized by receptor blockade. The data suggest that functional alterations of lymphocyte responses to nucleoside exposure are not a consequence of surface receptors for adenosine nucleosides in murine cells.