LACTATE PRODUCTION BY HUMAN MONOCYTES MACROPHAGES DETERMINED BY PROTON MR SPECTROSCOPY

Elevated brain lactate has been observed by in vivo proton MRS in diff erent pathological situations. The origin of this lactate remains cont roversial, The possibility that it was produced by the metabolism of p hagocytic cells has been proposed, To investigate this hypothesis, the authors have employed high-resolution proton MRS to monitor changes i n glucose, lactate, and other metabolites in the medium used to cultur e human monocyte-derived macrophages in vitro. Results show that the d ifferentiation of human monocytes/macrophages in the presence of physi ological stimulating factors (M-CSF or GM-CSF) was associated with an increase in lactate production and glucose utilization. The present re sults are consistent with the hypothesis that lactate detected by prot on MRS in vivo may be produced by the metabolism of macrophages when i nfiltrates of these cells are present, The possible extrapolation of t he authors' finding to the in vivo situation and its relevance are dis cussed.