Surface IgM and IgG expression was evaluated on IgD− memory B-cells and DN-memory B-cells (Fig. 2 A) as depicted in a representative blood and lung sample from an IPF patient and a healthy control in Fig. 2 B. The IgD−IgM−IgG− memory and IgM−IgG− DN-memory B-cells were enriched for IgA surface expression (Additional file 3: Figure S3 and Additional file 4: Figure S4). This evidence concerns the gene CD40LG and idiopathic pulmonary fibrosis.