The immune implication of the ANCA include suppression of the regulatory T-cells and increasing the pro-inflammatory state of these cells, also leading to B-cell hyperreactivity.9 Recently, it was found that anti-MPO and anti-PR3 are important in the physiopathology of pulmonary fibrosis (PF), which can lead to explain a lot of previously named idiopathic cases. This evidence concerns the gene MPO and pulmonary fibrosis.