Intravenousimmunoglobulin (IVIG) therapy caused similar effects thus suggesting that itstherapeutic effect could depend on modulation of IL1 isoforms and its receptor levels.Galle et al. [23] and Keskin et al. [17] revealed also that IVIG exertsanti-IL-6 properties thus to some extent, explaining mechanisms of its activityin PV patients. The gene discussed is IL1A; the disease is acquired polycythemia vera.