Conditions for maximal synthesis of cyclic AMP by mouse macrophages in response to β‐adrenergic stimulation

Abstract

of effector-regulator recognition or the mechanisms of control.However, these phenomena are best explained by the immunological network of Jerne [ 11. The antigen specificity we demonstrate would be the product of specific interactions between idiotypic effector cells and their anti-idiotypic regulators. Thus, we propose that the antagonistic relationship between the idiotypic effector clone and the regulatory antiidiotypic clone may be characterized by regular, cyclic behavior, perhaps in the form of Lotka-Volterra oscillations [ 171, even in the naive individual.The synthesis of cyclic AMP by mouse peritoneal macrophages in response to stimulation by isoproterenol was studied as a function of drug concentration, incubation time and cell density. Cyclic AMP levels of macrophages increased 3 to 3.5 times over the control level 20 sec after the addition of

Dynamics of the Macrophage Plasma Membrance

“…The incubation period required for increase in activity contrasts with those found in previ ous studies (83,84,163,282,293). Enzyme activity in stimulated guinea pig peritoneal macrophage homogenates in a separate study was responsive to fJ adrenergic catecholamines and the prostaglandins PGE1 and PGEz (207).…”

“…Elicited MPM respond to isoproterenol with a 3-to 3.5-fold increase in cAMP after 20 sec. As in the previous study, the increase in intracellular cAMP could be potentiated in the presence of phosphodiesterase inhibitors (282).…”

“…Increased adenyl ate cyclase activity resulting in increases in intracellular cAMP have been demonstrated in nonstimulated rabbit PAM (293), elic ited and nonelicited MPM (163,282), and rat and guinea pig peritoneal macrophages (83,84,207,208). Although a detailed kinetic analysis of macrophage adenylate cyclase has not been reported, this enzyme is respon sive to agents that enhance adenylate cyclase activity in other cell systems.…”

“…Several enzymes have been localized to the macrophage plasma membrane, including adenylate cyclase (83,84,163,207,208,282), alkaline phos phodiesterase I (64,278), aminopeptidase (270--273), ATPase (89,90,171), proteolytic enzymes capable of degrading serum amyloid (134), and 5' nucleotidase (62,63,120,137,286).…”

cAMP induces CD14 expression in murine macrophages via increased transcription

“…The second messenger cAMP has been shown to play a role in the regulation of macrophage function [36] and surface receptor expression [37,38]. Elevation of cAMP in macrophages can occur via activation of adenylate cyclase by agents such as ␤-adrenergic agonists, H-2 histamine receptor agonists, and prostaglandins E 1 and E 2 [39,40]. Moreover, increased intracellular cAMP levels also play a role in induction of CD14 expression during the dihydroxyvitamin D 3 -dependent differentiation of a human leukemic cell line to a monocytemacrophage phenotype [41], but the regulation of CD14 expression in this system was not fully characterized.…”