Direct stimulation of neutrophil oxygenation activity by serum from patients with systemic lupus erythematosus: A relationship to disease activity

Sera from patients with systemic lupus erythematosus (SLE) directly stimulate polymorphonuclear leukocyte (PMNL) oxygenation activity as measured by luminol dependent chemiluminescence (CL). The stimulatory capacity of a serum, expressed as percent PMNL chemiluminescence (%CL), was calculated by dividing the integral CL response to the serum by the integral CL response to a standard stimulus, opsonified zymosan. Testing was performed on 50 sera obtained serially from 8 SLE patients and on 14 sera from 11 controls. Sera from SLE patients in remission and controls were nonstimulatory with mean % CL ± SE values of 3.1 ± 0.7 and 3.5 ± 0.9, respectively. Sera obtained from the SLE patients during active disease yielded a mean %CL value of 26.6 ± 9.0. The stimulatory capacity of SLE serum was concentration dependent and enhanced by adding normal serum complement. The CL response correlated with serological measures of SLE activity such as antibodies to double stranded DNA (p<.0001) and Clq binding immune complexes (p<.001). Thus, during active SLE, PMNL may become metabolically activated by exposure to serum containing immune complexes and possibly other factors. PMNL activation may contribute to the development of vasculitis, leukopenia, and susceptibility to infection. Our CL approach allows sensitive in vitro assessment of the phlogistic properties of serum to monitor SLE disease activity.