Adenyl Cyclase Activity of Spleen Cells Exposed to Immunoenhancing Synthetic Oligo- and Polynucleotides

Abstract

Indirect evidence (1) indicates that cells responding to antigenic stimulation, like cells responding to hormone stimulation, may be activated by events that are mediated by adenosine 3′5′-monophosphate (cyclic AMP). The stimulation of antibody formation by cAMP, coupled with the capacity of theophylline, a stabilizer of cAMP levels, to magnify poly A:poly U-induced stimulation of specific antibody responses strongly suggested that an activation of adenyl cyclase, converting adenosine triphosphate (ATP) to cAMP, may take place following the interaction of antigen with appropriate recognition sites on membranes of immunocompetent cells (1). This conclusion was supported by the finding that cAMP can stimulate thymocytes (2) and human peripheral lymphocytes (3), and that phytohemagglutinin (PHA), a nonspecific activator of lymphocytes, increases adenyl cyclase activity of peripheral blood lymphocytes exposed to PHA in vitro (4). We have now collected direct evidence for increased adenyl cyclase activity in mouse spleen cells exposed in vitro to breakdown products of synthetic polynucleotides, which are known to be potent stimulators of specific immune responses in vivo and in vitro (5).