Evaluation of the use of the solvent dimethyl sulfoxide in chemiluminescent studies.

Dimethyl sulfoxide (DMSO) is extensively used as solvent in in vitro chemiluminescent studies, to dissolve stimulants, drugs, and luminescent probes. DMSO is also known to scavenge hydroxyl radicals. In this study the effect of DMSO on the superoxide production of the different white blood cells, neutrophils, eosinophils, lymphocytes, and monocytes, after stimulation with phorbol myristate acetate (PMA), opsonized zymosan (OZ), and formylmethionylleucylphenylalanine (fMLP), was determined. Neutrophils, eosinophils, lymphocytes, and monocytes were isolated from human blood. DMSO was added in different concentrations before the cells were stimulated to produce superoxides. Concentrations of 10, 8, and 6% (v/v) DMSO cause significant inhibition of superoxide production (SP) after PMA and OZ stimulation. This was extended to 4 and 2% (v/v) DMSO after fMLP stimulation. The SP rates of eosinophils, lymphocytes, and monocytes are nonsignificantly decreased except at 10% (v/v) DMSO for lymphocytes after PMA stimulation and 10, 8, and 6% (v/v) DMSO for monocytes after fMLP stimulation. Due to strong scavenging effects of DMSO, this solvent should be used with caution as solvent in chemiluminescent studies. Concentrations of less than 1% (v/v) DMSO should not interfere with the results. During chemiluminescent studies care must be taken to ensure that the total amount of DMSO in the cuvette should not exceed 1% of the total volume, especially if the drug, the luminescent probe, and the stimulant were dissolved in DMSO.