Elastase activity in serum and synovial fluid of patients with connective tissue disorders.

Sera and synovial fluids (SF) from patients with connective tissue disorders had significantly lower levels of elastase than sera from healthy controls. Patients with rheumatoid arthritis had significantly lower elastase activity in SF compared with serum. Elastase activity in serial serum samples from patients with systemic lupus erythematosus undergoing plasmapheresis showed some relationship with the clinical condition but little correlation with levels of circulating immune complexes. It was concluded that free elastase in the serum or SF was unlikely to be of much pathological significance in connective tissue disease.