Positive anti-cyclic citrullinated proteins and rheumatoid factor during active lung tuberculosis

To determine the prevalence of anti-cyclic citrullinated proteins (anti-CCP) and IgM rheumatoid factor (RF) in sera of patients with TB compared with healthy controls.

47 consecutive patients with recently diagnosed active pulmonary TB and 39 healthy controls were studied. Data were collected by questionnaire on clinical features of the disease, duration of symptoms, fever, cough, arthralgia, myalgia, sicca symptoms. Serum samples were collected from patients before starting treatment for TB and frozen at -20 degrees C. Anti-CCP and IgM RF were evaluated by ELISA.

The mean (SD) duration of TB related symptoms was 4.4 (1.7) months, 73% had fever, 94% a cough. Rheumatic symptoms were relatively rare: arthralgia (4%), myalgias (4%), eye and mouth dryness (2% and 9%, respectively). Mean (SD) levels of anti-CCP were significantly increased in patients with TB compared with controls: 44.9 (51) IU v 20 (7.3) IU (p = 0.002). Serum levels >40 U were found in 15/47 (32%) patients compared with 1/39 (2.6%) controls (p = 0.002). Mean (SD) serum levels of IgM RF were significantly increased in patients with TB: 17.8 (19) v 4.3 (5) (p<0.0001). IgM RF was positive (>6 IU) in 29/47 (62%) patients v 1/39 (2.6%) controls (p<0.0001).

A significant proportion of patients with active TB have an increased titre of anti-CCP and IgM RF.