Abstract
Case report: A patient with RA resistant to repeated high dose infliximab infusions and intra-articular infliximab into an inflamed knee is described. No beneficial clinical effect was observed. Pre-injection arthroscopic biopsy of the study knee demonstrated TNFα staining but also confirmed the presence of lymphotoxin α (LTα or TNFß) on immunohistochemistry. Subsequent treatment with etanercept (which blocks LTα as well as TNFα) resulted in clinical remission of disease.
Conclusion: This case suggests that resistance to TNF blockade may occur when TNFα is not the dominant inflammatory cytokine and suggests that LTα may have a pathogenic role in RA.
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Figure 1.
Panels (A) and (D) are the negative controls for the study patient and positive control respectively. Panels (B) and (E) demonstrate TNFα expression detected with anti-TNFα monoclonal mouse IgG1 clone 28401 in the study patient and positive control, respectively. Panels (C) and (F) demonstrate LTα expression detected with anti-LTα monoclonal mouse IgG1 clone 5802.21 in the study patient and positive control, respectively.