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Improved Sensitivity of Skin Pathergy Test with Polysaccharide Pneumococcal Vaccine Antigens in the Diagnosis of Behçet Disease.

OBJECTIVE
The skin pathergy test (SPT) is an important tool in the diagnosis of Behçet Disease (BD), but its decreasing sensitivity over years has limited its use. This study aimed to improve the sensitivity of SPT without compromising its specificity.


METHODS
BD patients, patients with other inflammatory diseases, recurrent aphtous stomatitis, and healthy controls were comprised the study group. SPT was induced by 20G needle and 21G lancet pricks, or with additional application of 23-valent polysaccharide pneumococcal vaccine (PS-23), Alum, or ATP to prick site. Development of erythema and induration at 24 h/48h were evaluated by the same observer. Induration (≥2 mm) with erythema at 48 h was accepted as positive. Proinflammatory cytokine production following stimulation with LPS or PS-23 was investigated by whole blood assay (WBA) in a subgroup.


RESULTS
Stimulation of forearm skin by PS-23 and 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 the sensitivity of 4.8% in all and 6.1% in active patients using a single 20G prick. Positive result was associated with the disease activity and not using immunosuppressives. In WBA, increased IL-1β and IL-1Ra production in response to PS-23 was observed in active BD group, while cytokine response to LPS was similar in all groups.


CONCLUSION
SPT induced by 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 applications.