FLOW CYTOMETRICAL DETERMINATION OF INTERLEUKIN 1β, INTERLEUKIN 6 AND TUMOUR NECROSIS FACTOR α IN MONOCYTES OF RHEUMATOID ARTHRITIS PATIENTS; RELATION WITH PARAMETERS OF OSTEOPOROSIS

Abstract

Experimental data suggest that pro-inflammatory cytokines such as interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumour necrosis factor α (TNF-α) are important in the pathogenesis of osteoporosis in rheumatoid arthritis. Therefore we compared the production of these cytokines by monocytes in 10 rheumatoid arthritis patients and 10 controls. Cytokine levels in rheumatoid arthritis patients were related to disease activity parameters, bone mineral density (BMD) corrected for age and sex (Z scores) and osteocalcin as a laboratory parameter of bone remodelling. Cytokines were determined by a flow cytometrical technique. There was a tendency for higher IL-1β levels in patients compared with controls. A positive correlation between erythrocyte sedimentation rate and spontaneous production of monocytic cytokines was found. Z scores of the lumbar spine showed a negative correlation with spontaneous production of IL-1β and IL-6. Plasma osteocalcin levels were positively correlated with spontaneous production of IL-1β, IL-6 and TNF-α. In conclusion, the correlation of the levels of these cytokines with parameters of bone metabolism and osteoporosis suggest that especially IL-1β and IL-6 are associated with more pronounced osteoporosis in active rheumatoid arthritis.