034 Basophil activation and low levels of circulating basophils correlate with clinical severity in bullous pemphigoid

Basophils are rare immune cells, accounting for 0-2% of peripheral blood leukocytes, and known to be involved in defense against parasitic infections allergic diseases. Recent studies have revealed their pathogenic role autoimmune diseases such as systemic lupus erythematosus via type 2 cytokine production supporting plasma cells. Bullous pemphigoid (BP) is an blistering disease caused by IgG autoantibodies targeting collagen XVII (COL17) BP230. IgE observed 20-70% BP patients. induces stimulation degranulation basophils mast cells high-affinity receptor FcεRI. Activated been reported the lesional skin patients, but remains unclear. To elucidate relevance severity, we investigated how bullous area index (BPDAI) relates basophil activation counts. We analyzed marker CD203c mean fluorescence intensity (MFI) from active-phase The MFI correlated with BPDAI. additionally performed a test stimulating recombinant COL17 patients remission. Stimulation positively BPDAI before treatment, suggesting that may stimulate binding BP-IgE exacerbate inflammation. Furthermore, counts negatively BPDAI, indicating migration lesions severe Our findings suggest present acute phase, which might stimulated COL17. migrate