Functional Fc-receptor defect of polymorphonuclear leukocytes in a patient with Sjögren's syndrome

We investigated polymorphonuclear leukocyte (PMN) function in a 50-year-old woman with primary Sjögren's syndrome (SS). The respiratory burst of PMN was monitored by luminol-enhanced chemiluminescence using zymosan, opsonized zymosan, zymosan-activated serum, and phorbol-myristate-acetate, as well as serial dilutions of aggregated immunoglobulin (aggIg) as Fc-receptor (FcR) stimulus. The effects of serum on the chemiluminescent response as well as the binding of aggIg to PMN were also compared. We found the patient's PMN not to respond to stimulation by aggIg, only the highest concentration (greater than 180 micrograms/ml) induced a marginal chemiluminescent response in the patient. By contrast, incubation of the patient's PMN with other stimuli resulted in responses similar to those in a healthy control. Binding of aggIg to PMN was higher in the patient (3.6% vs 1.5% of the radioactivity added in the control). Sera of patient and control induced similar chemiluminescence on PMN as did that of another human serum. Our data indicate a selective functional FcR defect of PMN despite unimpaired binding of aggIg in a patient with SS.