Nitroblue tetrazolium dye reduction by peripheral leukocytes from rheumatoid arthritis and systemic lupus erythematosus patients measured by a histochemical and spectrophotometric method

Abstract Phagocytic activity of peripheral leukocytes in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients was measured by in vitro reduction of nitroblue tetrazolium (NBT) dye employing histochemical and spectrophotometric methods. Neutrophils from rheumatoid patients reduced dye normally. Resting SLE neutrophils had lower mean NBT dye reduction than normal control or rheumatoid neutrophils. This decrease in NBT reduction was statistically significant. SLE patients treated with suppressive doses of prednisone (> 10 mg. per day) as well as untreated patients demonstrated this abnormality. SLE neutrophils stimulated by in vitro phagocytosis of latex particles demonstrate an incremental increase in NBT dye reduction comparable to normal control and RA neutrophils. Infected SLE patients, both untreated and steroid-treated cases, failed to demonstrate the anticipated increase in NBT dye reduction. This study presents data indicating that the histochemical and spectrophotometric procedure for measuring NBT dye reduction can be modified to yield comparable results. The current findings support other investigations that have shown serum and/or cell-mediated defects in phagocytosis can be detected in leukocytes obtained from SLE patients.