S100A8 and anti-neutrophil cytoplasmic antibody-associated vasculitis: The possible reason why in our study we did not find a difference between patients with IgAVN compared to other patients with IgAV is, therefore, that in patients with IgAV, regardless of the clinical phenotype of the disease, and similar to patients with AAV, neutrophils in the blood could be activated (which is associated with an increase in the serum level of S100A8/A9), and in patients with IgAVN there is an additional accumulation of macrophages in the kidney and an increase in the expression of S100A8/A9 on glomerular macrophages.