AJP - Endocrinology and Metabolism, Vol 264, Issue 1 E24-E28, Copyright © 1993 by American Physiological Society
Effects of glucocorticoids on lymphocyte metabolism
M. A. Serrano, R. Curi, M. Parry-Billings, J. F. Williams and E. A. Newsholme
Department of Physiology and Biophysics, Sao Paulo University, Brazil.
The immunosuppressive effect of glucocorticoids has been widely reported;
however, the mechanism of action of these hormones on the immune system has
not been fully established. In the present study, the effect of
glucocorticoids on glucose, glutamine, and pyruvate metabolism in lymph
node lymphocytes was investigated. Addition of dexamethasone to the
incubation medium did not alter glucose and glutamine metabolism but
inhibited pyruvate utilization by 40%. This latter effect took 1 h to occur
and remained for up to 6 h, even after removal of dexamethasone from the
culture medium. Measurements of the activity of pyruvate dehydrogenase in
lymphocytes and the rate of [1-14C]-pyruvate conversion into 14CO2 in
incubated lymphocyte mitochondria demonstrated that glucocorticoids
decrease pyruvate utilization by inhibiting the activity of this key
regulatory enzyme. The effect of such an inhibition of pyruvate utilization
on the function of cells of the immune system remains to be clarified.
