Purified protein derivative response in juvenile idiopathic arthritis

Area of Science:

• Immunology
• Pediatrics
• Rheumatology

Background:

• Juvenile idiopathic arthritis (JIA) is a chronic autoimmune disease affecting children.
• The bacillus Calmette-Guerin (BCG) vaccine is used to prevent tuberculosis and elicits a T-helper 1 (Th1) immune response.
• Assessing Th1 immune response is crucial for understanding immune function in JIA patients.

Purpose of the Study:

• To investigate the purified protein derivative (PPD) skin test response in children diagnosed with JIA.
• To evaluate if the PPD response, a marker of Th1 immunity, differs between children with JIA and healthy controls.
• To determine the impact of BCG vaccination status on PPD response in JIA.

Main Methods:

• A PPD skin test was administered to 115 children with JIA and 45 healthy children, all previously vaccinated with BCG.
• PPD positivity was defined as an induration of ≥5 mm, with ≥10 mm considered indicative of tuberculosis suspicion.
• Statistical analysis compared PPD induration sizes and positivity rates between JIA patients and controls.

Main Results:

• Children with JIA exhibited significantly lower PPD induration sizes and positivity rates compared to healthy controls.
• The mean PPD induration was substantially smaller in JIA patients (3.7–10.05 mm) than in controls (7.10–10.05 mm), regardless of BCG vaccination count.
• PPD positivity was 35.9% in JIA patients vaccinated once and 50% in those vaccinated more than once, versus 82.1% and 88.2% in respective control groups.

Conclusions:

• The Th1 cell-mediated immune response, as indicated by the PPD test, is significantly attenuated in BCG-vaccinated children with JIA.
• This diminished PPD response in JIA patients suggests a potential alteration in their cellular immune function.
• Disease activity or treatments like corticosteroids and methotrexate did not appear to influence the PPD response in this cohort.