In RA, response to TNF blockers may be associated with a profile of cytokine production unique to each patient. This study sought to predict the response to biologic agents by examining pro-inflammatory cytokine synthesis in stimulated whole blood cultures (WBCs).
We measured the concentration of TNF-α, IL-1β and IL-6 in supernatants of lipopolysaccharide (LPS)-stimulated WBCs obtained from RA patients (n = 41) before anti-TNF therapy (infliximab, 13; etanercept, 26; and adalimumab, 2) and from healthy controls (n = 12). At 24 weeks after biologics, whole bloods were again drawn from 14 of 41 patients. Response was defined by the European League Against Rheumatism response criteria after 24 weeks of therapy.
Among 41 patients, 32 were responders (good 14/moderate 18), while 9 were non-responders. All cytokines measured were significantly lower in RA patients than in controls. In RA, IL-1β production was lower in non-responders than in responders [median (interquartile range): 3.5 (1.5-9.4) vs 10.0 (5.1-93.1) pg/ml, P = 0.048]. The area under the curve from a receiver operating characteristic curve analysis for the prediction of response using IL-1β was 0.717 (95% CI 0.520, 0.914). The sensitivity and specificity of IL-1β (cut-off value 4.84 pg/ml) was 78.1 and 77.8%, respectively. All cytokines were significantly higher 6 months later compared with their respective baseline.
IL-1β measurement in LPS-stimulated WBC is useful to predict responsiveness to anti-TNF agents. Cytokine production capacities in LPS-stimulated WBCs are up-regulated by biologics.