Autoantibodies against interleukin 1alpha in rheumatoid arthritis: association with long term radiographic outcome

Abstract

Objectives: To investigate the possible association of interleukin 1alpha autoantibodies (IL1alpha aAb) with the long term course of joint erosion in patients with rheumatoid arthritis (RA).

Methods: Serum samples from 176 patients with RA included in a prospective study over 30 years were analysed for IL1alpha aAb by binding to human [(125)I]IL1alpha. Erosions of 19 diarthrodial joints were radiographically scored by the Larsen method.

Results: The relative risk (RR) of early IL1alpha aAb positive patients developing at least 30% of maximum radiographic joint destruction was significantly lower than for IL1alpha aAb negative patients, RR=0.29 (p=0.04). In rheumatoid factor positive patients RR was only 0.18 (p=0.02). Patients who seroconverted more than two years after the onset of RA showed the most aggressive development of joint erosion, with a relative risk of at least 40% of maximum radiographic joint destruction of 2.56 (p=0.048)

Conclusions: The progression of radiographic joint destruction in patients with RA is associated with, and perhaps modified by, circulating IL1alpha aAb, suggesting that IL1alpha or IL1alpha aAb, or both, have a role in the erosive processes. IL1alpha aAb appear to be of prognostic significance in RA.

Figure 1

Effect of early IL1α aAb positivity on joint erosions in patients with RA. Kaplan-Meier plots of radiographic events defined as 30% and 40% of maximal radiographic destruction (RE30, RE40). The two patient groups are defined by the presence and absence of IL1α aAb during the first two years after onset of the disease. p Value: log rank test.

Figure 2

Effect of early IL1α aAb positivity on joint erosions in rheumatoid factor positive patients with RA. Kaplan-Meier plots are as in fig 1. The two patient groups are defined by the presence and absence of IL1α aAb during the first two years after onset of the disease. p Value: log rank test.

Figure 3

Effect of late IL1α aAb seroconversion on joint erosions. Kaplan-Meier plots are as in fig 1. The two patient groups are defined as those permanently negative for IL1α aAb and those initially negative who seroconverted more than two years after onset of the disease. p Value: log rank test.