ANTIMYELOPEROXIDASE ANTIBODIES IN INDIVIDUALS WITH OCCUPATIONAL EXPOSURE TO SILICA

Objective-To determine the prevalence of autoantibodies to myeloperoxi dase (MPG) in a series of patients exposed to silica. Methods-The stud y included 52 patients with occupational exposure to silica (mean expo sure time seven years) and a control group comprising seven patients w ith progressive systemic sclerosis (PSS), six patients with systemic l upus erythematosus (SLE), and 15 healthy individuals. Antibodies to MP O were detected using commercial enzyme linked immunosorbent assay (EL ISA) plates coated with MPO. Indirect immunofluorescence studies for a ntineutrophil cytoplasmic antibodies were performed using ethanol and formol fixed neutrophils. Clinical and biological data of individuals exposed to silica were recorded (published previously). Results-Antibo dies to MPO were detected in 14 individuals exposed to silica (27%). T here was a statistically significant difference in anti-MPO ELISA unit s between the healthy subjects and patients (SLE, PSS, silica exposed individuals) (p < 0.01), but no difference between the different disea se groups. Conclusions-Individuals chronically exposed to silica, whet her or not they have a connective tissue disease, have levels of antib odies to MPO (as detected by ELISA) that are greater than those found in the normal population, but similar to those in patients with system ic diseases not induced by silica (SLE/PSS).