Purified protein derivative response in juvenile idiopathic arthritis.

OBJECTIVE

To examine the purified protein derivative (PPD) response that develops depending upon Th1 immune response in children with juvenile idiopathic arthritis (JIA).

METHODS

PPD skin test was performed in 115 children with JIA who were vaccinated with bacillus Calmette-Guerin (BCG), and then they were compared to the PPD response of 45 healthy children of the same age who were vaccinated with BCG. Children with a PPD induration > or = 5 mm were accepted as PPD-positive. PPD induration > or = 10 mm was accepted as a limit for suspecting tuberculosis.

RESULTS

PPD induration size and PPD positivity rates (PPD > or = 5 mm) of children with JIA were significantly lower than those of healthy children. The mean of PPD induration size was significantly lower (p < 0.0001) in patients with either 1 BCG vaccine (3.7 +/- 3.6) or more than 1 BCG vaccine than controls with either 1 BCG vaccine (7.10 +/- 3.2) or more than 1 BCG vaccine (10.05 +/- 4.1). PPD was positive in 35.9% of patients with JIA vaccinated once (n = 32), in 50% of patients with JIA vaccinated more than once (n = 13), in 82.1% of controls vaccinated once (n = 23), and in 88.2% of controls vaccinated more than once. This result was statistically significant (patients, p = 0.03; controls, p = 0.039). It was determined that neither the activity of the disease nor the use of corticosteroid and methotrexate affected the PPD response.

CONCLUSION

The response to PPD, which is one of the Th1 cell-type responses, was significantly lower in BCG-vaccinated children with JIA compared to healthy children.