Elevated nerve growth factor levels in synovial fluid of patients with inflammatory joint disease

Abstract

A novel pH shock extraction procedure was used to measure nerve growth factor (NGF) levels in both normal and inflamed synovial fluids using a sensitive and specific two-site enzyme linked immunosorbant assay. To date no data is available on NGF levels in normal synovial fluids. Synovial fluids were taken from 5 normal volunteers, 12 patients with rheumatoid arthritis and 10 patients with other inflammatory arthropathies. The mean ± SEM NGF concentration in normal synovial fluids was 95 ± 33.2 pg/ml (range 39.1–143.1 pg/ml), whereas the mean NGF concentration in the synovial fluids taken from patients with rheumatoid arthritis was 532.5 ± 123.8 pg/ml (range 152–1686 pg/ml). The mean NGF concentration in patients with other inflammatory arthropathies was also raised (430.6 ± 90 pg/ml; range 89–1071 pg/ml). The NGF concentrations were significantly higher in the synovial fluids from both inflamed groups (ANOVA p < 0.05)="" compared="" to="" normals.="" raised="" levels="" of="" ngf="" in="" synovial="" fluid="" may="" contribute="" directly="" to="" joint="" inflammation="" via="" activation="" of="" inflammatory=""