The Role of Anti-SSB/La Antibodies as Predictors of Decreased Diffusing Capacity of the Lungs for Carbon Monoxide (DLCO) in Primary Sjögren Disease

Lung involvement is the most common extraglandular manifestation of primary Sjögren's Disease (pSjD). There is an increasing interest in finding the clinical/serological risk predictors of this feature. A cross-sectional study evaluating anti-SSA/Ro antibodies, anti-SSB/La antibodies, rheumatoid factor, antinuclear antibodies, and the diffusing capacity of the lungs for carbon monoxide (DLCO) in 26 pSjD patients who presented interstitial changes on the chest CT scan was performed. The titres and positivity rates for anti-SSA/Ro (<i>p</i> = 0.02, <i>p</i> = 0.02) and anti-SSB/La antibodies (<i>p</i> = 0.01, <i>p</i> = 0.001) proved to be significantly increased in patients with abnormal DLCO. Anti-SSB/La antibodies' titres seemed to be the best predictor for decreased DLCO-AUC 0.791 (0.587-0.994), <i>p</i> = 0.016. A close-to-significance decrease was found in the titres (<i>p</i> = 0.07) and positivity rates-<i>p</i> = 0.09 and OR of 0.15 (0.01-1.63)-of anti-SSB/La antibodies in patients with usual interstitial pneumonia (UIP), indicating their possible protective role against UIP. The lymphocytic interstitial pneumonitis (LIP) pattern on lung CT scan was significantly associated with the simultaneous positivity of the four examined serological markers (<i>p</i> = 0.03). The increase in anti-SSB/La antibody positivity rate in patients with LIP patterns was situated close to the significance level (<i>p</i> = 0.09). Quadruple positivity, as well as isolated anti-SSB/La positivity, could be risk factors for developing LIP in pSjD patients. Thus, anti-SSB/La antibodies might represent a marker of lung involvement in pSjD patients.