Fig. 4. Lactic acidosis is associated with pseudostarvation.

a–e Monocytes were polarized into macrophages in the absence (Mφ) or presence of lactic acid (LA-Mφ), lactic acid and acetoacetate (LA-Mφ + AcAc), or under acidosis (HCl-Mφ). Glucose (a), glutamine (b), free l-amino acids (c), and lactate (d) were quantified at days 3, 5, and 7 in cell culture supernatants of Mφ, LA-Mφ, LA-Mφ + AcAc, and HCl-Mφ. Results are expressed in µmol/10⁶ cells/24 h, with positive values for consumption and negative values for production (mean ± SD; Mφ and LA-Mφ: n = 6; HCl-Mφ: n = 4 (a) or n = 5 (d); LA-Mφ + AcAc: n = 4 (a, b) or n = 5 (c, d)). e Intracellular pH was measured by flow cytometry with the SNARF probe. Monocytes were loaded with the SNARF probe and analyzed for 30 s before the addition (arrow) of 10 mM lactic acid (LA-Mφ), with or without 5 mM acetoacetate (LA-Mφ + AcAc). The acquisition was then prolonged for an additional 30 min. Probe loading and acquisition were repeated at 24 h. Representative results from one of three independent experiments are shown. f Acetoacetate (AcAc) was quantified on days 1 and 3 in LA-Mφ + AcAc culture supernatants (n = 5). Results are expressed in µmol/10⁶cells/24 h. a–f The boxplots display a median line, interquartile range (IQR) boxes, min to max whiskers; a two-tailed Mann–Whitney U test was performed for statistical analysis. Source data are provided in a Source Data file.