RHEUMATOID SERA AND SOLUBLE COMPLEXES: NITROBLUE TETRAZOLIUM DYE TEST AND HEXOSE MONOPHOSPHATE SHUNT ACTIVATION

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Abstract
An increased number of cells containing reduced dye in the nitroblue tetrazolium (NBT) test were observed when peripheral blood leukocytes of adult rheumatoid arthritis (RA) patients having rheumatoid factor (RF), as well as RF-negative pediatric RA patients were studied. Therefore, the relationship between soluble antigen -antibody complexes and NBT dye reduction following phagocytosis was investigated. After intravenous injection of 131I labeled bovine serum albumin (IBSA) into six rabbits, the mean onset of immune clearance was 8.2 days (range, 7 to 9). NBT-positive cells increased from control levels (3% to 10%) at four to six days and were maximal at six days. The mean maximal response was 35% (range, 22% ot 47%). In vitro studies of the hexose monophosphate (HMP) shunt activity of human leukocytes exposed to BSA-anti-BSA complexes demonstrated a twofold to threefold stimulation in the range of slight antigen excess. Leukocyte NBT reduction was not consistently increased above that of the controls. However, when high titer RF sera was incubated with normal human leukocytes, maximal NBT responses were observed when the RF titer was 200 to 600 units (mean, 27%; controls, 2% to 8%) and 14CO2 evolution via the HMP shunt was accelerated. RF-negative sera from children with RA elicited a slight increase in NBT-positive cells and a definite increase in 14CO2 evolution was observed. It was then concluded that soluble antigen-antibody complexes in slight antigen excess altered hexose monophosphate shunt activity and increased NBT dye reduction. The NBT-positive cell in RA may be due to phagocytosis of RF accompanied by metabolic activation.

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