Effect of Immunization on the Cyclic AMP Level and 3H-Thymidine Incorporation in Cultured Lymphoid Cells

Abstract

The cyclic AMP level and the uptake of ³H-thymidine were studied in short-term suspension cultures of guinea pig lymphoid cells. Spleen cells from animals immunized 3 days previously with typhoid vaccine were shown to differ in three respects from the normal cells: (1) The level of cyclic AMP was higher. (2) The cyclic AMP increase following addition of isoproterenol or adenosine was abolished. (3) Isoproterenol (10^-5 to 10^-4M) stimulated the uptake of ³H-thymidine in cells from immunized animals, while the uptake into normal cells was inhibited by these concentrations. A higher dose of isoproterenol (10^-3M) inhibited ³H-thymidine uptake in both immunized and normal cells. The results reveal certain biochemical alterations in splenic lymphocytes after immunization. An altered ³H-thymidine uptake may be caused by the modified cyclic AMP metabolism in cells from immunized animals.