Objectives. To investigate proinflammatory cytokine expression in temporal arteries from patients with giant-cell arteritis (GCA) and to analyse its relationship with the intensity of the initial systemic inflammatory reaction and response to corticosteroid therapy.

Methods. Quantification of interleukin-1β (IL-1β), tumor necrosis factor α (TNFα), and interleukin-6 (IL-6) mRNA by real-time quantitative PCR in temporal artery samples from 36 patients with biopsy-proven GCA and 11 controls. Immunohistochemical detection of IL-1β, TNFα, and IL-6 in temporal artery sections from 74 patients with GCA and 15 controls. Clinical and biochemical parameters of inflammation as well as the time (weeks) required to reach a maintenance prednisone dose <10 mg/day were recorded.

Results. IL-1β (13.8 ± 2.5 vs 5.4 ± 1.3 relative units, P = 0.012) and IL-6 transcripts (34 ± 13.7 vs 7.8 ± 4.5 relative units, P = 0.034) were significantly more abundant in patients with a strong systemic inflammatory response compared with those with no inflammatory parameters. Immunohistochemical scores for IL-1β (2.7 ± 0.3 vs 1.9 ± 0.2, P = 0.018), TNFα (3.2 ± 0.2 vs 2.4 ± 0.3, P = 0.028) and IL-6 (3 ± 0.2 vs 2.1 ± 0.3, P = 0.023) were also significantly higher in patients with strong systemic inflammatory reaction. A significant correlation was found between the amount of tissue TNFα mRNA and the time required to reach a maintenance dose of prednisone <10 mg/day (r = 0.586, P = 0.001).

Conclusion. GCA patients with a strong systemic inflammatory response, who have been previously shown to be more resistant to corticosteroid therapy, have elevated tissue expression of proinflammatory cytokines IL-1β, TNFα and IL-6. High production of TNFα is associated with longer corticosteroid requirements.