Improved sensitivity of the skin pathergy test with polysaccharide pneumococcal vaccine antigens in the diagnosis of Behcet disease

Objective The skin pathergy test (SPT) is an important tool in the diagnosis of Behcet disease (BD), but its decreasing sensitivity over years has resulted in less frequent use in the clinical practice. This study aimed to improve the sensitivity of the SPT without compromising its specificity. Methods BD patients, patients with other inflammatory diseases, recurrent aphthous stomatitis, and healthy controls comprised the study group. The SPT was conducted using 20G needle and 21G lancet pricks, or with additional application of 23-valent polysaccharide pneumococcal vaccine (PS-23), Alum, or ATP to the prick site. Development of erythema and induration at 24 h/48 h were evaluated by the same observer. Induration (>= 2 mm) with erythema at 48 h was accepted as a positive reaction. Proinflammatory cytokine production following stimulation with lipopolysaccharide or PS-23 was investigated by whole-blood assay (WBA) in a subgroup. Results Stimulation of the forearm skin by PS-23 and a 20G needle prick showed the highest sensitivity and specificity in BD (64.3% and 100%, respectively), especially in patients with active disease (80.3% and 100%, respectively), compared with a sensitivity of 4.8% in all and 6.1% in active patients using a single 20G prick. A positive result was associated with active disease and no use of immunosuppressives. In WBA, increased IL-1 beta and IL-1Ra production in response to PS-23 was observed in the group with active BD, while the cytokine response to lipopolysaccharide was similar in all groups. Conclusions The SPT conducted using a 20G needle prick and PS-23 antigens was shown to be a promising tool for the diagnosis of BD owing to its improved sensitivity compared with the standard approach.