Fig. 3. The anti-inflammatory drug methotrexate does not influence the release of adenosine from fMLP-stimulated neutrophils. Human PMNs were stimulated with fMLP, alone or in the presence of CGS 21680, or with the anti-inflammatory compound methotrexate (MTX; 1 µM), or with adenosine deaminase (ADA), as described in Materials and Methods. At indicated time points, samples were processed for the measurement of extracellular adenosine by mass-spectrometry.