Anti-inflammatory drug may unleash TB

Physicians prescribing a drug that counteracts arthritis and other inflammatory diseases may in rare cases awaken dormant tuberculosis, researchers report in the Oct. 11 New England Journal of Medicine.

The drug, called infliximab and known by the trade name Remicade, suppresses a protein called tumor necrosis factor-alpha, or TNF-alpha, an immune system protein that causes swelling.

Physician Joseph Keane of Boston University School of Medicine noticed that a patient on infliximab had come down with tuberculosis. Keane, who studies TNF-alpha when he’s not seeing patients, recalled earlier reports that TNF-alpha protects mice from tuberculosis. So, Keane and his colleagues reviewed 69 other cases of tuberculosis in patients with inflammatory conditions who also had received infliximab. Most of the 70 patients were living in the United States or Europe.

From the results, the researchers estimated that the incidence of TB among rheumatoid arthritis patients receiving infliximab in the United States is more than 24 in 100,000 people. Among rheumatoid arthritis patients not getting infliximab, the rate is about 6 per 100,000.

The findings suggest that some people have smoldering, symptom-free TB that infliximab allows to flare up. Keane says that anyone about to start infliximab therapy should receive a TB skin test, to reveal any tuberculosis infection.