Kuzmina and colleagues observed that patients with newly diagnosed BOS had significantly increased relative numbers of CD19+CD21low B-cells (25.5 versus 6.6%, p < 0.0001) and BAFF/CD19+ ratio (0.18 versus 0.02 ng/103 CD19+ B-cells, p = 0.007) compared with patients without cGvHD (16). Here, CD19 is linked to Buschke-Ollendorff syndrome.