Cyclic AMP metabolism in asthma: Studies with leukocytes and lymphocytes

Abstract

The effect of isoproterenol on cyclic AMP (cAMP) levels in lymphocytes and leukocytes from asthmatic and normal individuals has been studied. Lymphocyte cAMP levels rose in response to 10 −8 to 10 −2 M isoproterenol; the dose-response curve was biphasic with a maximum response at concentrations of 10 −6 to 10 −4 M. At all drug concentrations the response of cells from asthmatic individuals was less than the response of cells from normal control subjects. The difference between the two groups was not statistically significant, however. Similarly, basal cAMP levels were lower in the cells of asthmatic as compared with normal individuals, but again the difference was not significant. When these two parameters were combined and the results expressed as absolute cAMP levels after isoproterenol treatment, a significant difference was observed. Both the unstimulated. cAMP levels and the response to isoproterenol of leukocytes from normal and asthmatic subjects were influenced by the incubation medium. Use of a medium buffered with tris as compared with bicarbonate-phosphate resulted in lower basal cAMP levels and increased responsiveness to isoproterenol. Treatment of normal leukocytes with serum from asthmatic individuals did not alter their response to isoproterenol.