INHIBITION OF 3H-THYMIDINE INCORPORATION BY ADENOSINE AND DEOXYADENOSINE IN HUMAN PERIPHERAL LYMPHOCYTES AND MALIGNANT LYMPHOID CELL LINES: 218

Abstract

Children with ADA deficiency have an impairment of both cellular and humoral immunity. We performed a detailed study of the relative toxicities of the ADA substrates adenosine and deoxyadenosine with regard to 3H-thymidine incorporation in mitogen-stimulated human peripheral blood lymphocytes and malignant lymphoid cell lines. Lymphocytes, isolated by Percoll gradient centrifugation and counterflow elutriation, were stimulated with various mitogens (PHA, ConA, PWM, SpA, StA) known to activate different lymphocyte subpopulations. Both lymphocytes and lymphoid cell lines were incubated with various adenosine and deoxyadenosine concentrations in presence of the ADA inhibitor deoxycoformycin. Combinations of deoxycoformycin and adenosine or deoxyadenosine gave inhibition of 3H-thymidine incorporation in both lymphocytes and cell lines. Adenosine affected 3H-thymidine incorporation of mitogen-stimulated lymphocytes to a similar extent as deoxyadenosine. However, to the malignant T cell line Molt 4 deoxyadenosine was more toxic than adenosine. This was not observed with the cell lines REH (nonBnonT), KM-3 (nonBnonT) and RAJI (B).Lymphocytes stimulated with B- or T cell mitogens were affected in their thymidine incorporation to a comparable extent by adenosine and deoxyadenosine. The cell line Molt was more sensitive to deoxyadenosine than both stimulated lymphocytes and the cell lines REH, KM-3 and RAJI.