Neutrophil functions in rheumatoid arthritis

Neutrophils play an important role in the pathogenesis of rheumatoid arthritis by accumulation and liberation of active proteolytic enzymes. Despite the active participation of the neutrophils, the patients afflicted with rheumatoid arthritis are prone to multiple infections. We studied neutrophil functions in 20 rheumatoid arthritis patients in active disease and equal number in remission and 20 healthy normal controls. No change in neutrophil function was seen in patients in remission. Phagocytic capacity of the neutrophils in active disease was found to be significantly reduced (p < 0.05). This inversly correlated with the rheumatoid factor (r = -0.128, p = 1). Random migration and chemotaxis was statistically reduced when compared with either healthy controls (p < 0.01) or when compared with patients in remission (p < 0.01). The chemotaxis inhibition was further enhanced by autologus serum (p < 0.05). The serum from patients with active disease also reduced chemotaxis of neutrophils from normal individuals (p < 0.01), indicating reduced cellular response as well as inhibitors in serum. The positive correlation (r = 0.466, p < 0.01) with rheumatoid factor, suggests the inhibitory activity may be due to the circulating rheumatoid factor in the active disease. The postulate that prior saturation of neutrophil receptors with immune complexes lower phagocytosis as well as chemotaxis is sustained. Destruction of chemotaxis receptors by release of various strong oxidative enzymes by neutrophils may also be a factor. Normal leucocytes are seen to take up immunoglobulins from diseases serum but not from normal serum. This uptake of diseased serum may be responsible for reducing the chemotactic and phagocytic function of neutrophils and hence increased incidence of infection in these patients.