Here, we observed that the addition of PGE2 (10 μM, i.e. 3525 pg/ml), in the range measured in COVID-19 patients’ sera (1300 to >20.000 pg/ml), to two human B-cell precursor lines, 697 and SUP-B15, significantly reduced PAX5 mRNA expression (Fig 4A and 4B). This evidence concerns the gene PAX5 and COVID-19.