Two published randomized controlled trials have reported on significant reductions in disease activity in patients with ankylosing spondylitis and other spondyloarthropathies who were treated with infliximab. Spondyloarthropathy (literally arthritis of the spine) may be associated with ankylosing spondylitis, Reiter's syndrome, reactive arthritis, psoriatic arthritis, and inflammatory bowel disease, or may be idiopathic (undifferentiated spondyloarthropathy). Van den Bosch et al (2002) reported on a 12-week long clinical study involving forty patients with active spondyloarthropathy who were randomly assigned to receive an intravenous loading dose (weeks 0, 2, and 6) of 5 mg/kg infliximab or placebo. Both patient and physician global assessments of disease activity on a visual analog scale improved significantly in the infliximab group compared with the baseline value, with no improvement in the placebo group. As early as week 2 and sustained up to week 12, there was a highly statistically significant difference between the values for these 2 endpoints in the infliximab versus the placebo group. In most of the other assessments of disease activity (laboratory measures, assessments of specific peripheral and/or axial disease), significant improvements were observed in the infliximab group compared with the baseline value and compared with placebo. There was 1 severe drug-related adverse event, in which a patient developed disseminated tuberculosis.
Glucocorticoids are potent anti-inflammatories, regardless of the inflammation's cause; their primary anti-inflammatory mechanism is lipocortin-1 (annexin-1) synthesis. Lipocortin-1 both suppresses phospholipase A2 , thereby blocking eicosanoid production, and inhibits various leukocyte inflammatory events ( epithelial adhesion , emigration , chemotaxis , phagocytosis , respiratory burst , etc.). In other words, glucocorticoids not only suppress immune response, but also inhibit the two main products of inflammation, prostaglandins and leukotrienes . They inhibit prostaglandin synthesis at the level of phospholipase A2 as well as at the level of cyclooxygenase /PGE isomerase (COX-1 and COX-2),  the latter effect being much like that of NSAIDs , potentiating the anti-inflammatory effect.