The mechanism underlying the beneficial effect of this therapy is not completely understood, but is likely to be related to the marked reduction in the IgE level. Of note is the concomitant accumulation of IgE-anti-IgE complexes in the sera. Another remarkable effect of the treatment is the substantial reduction in the FcεRI level on basophils, which is likely a key factor contributing to the therapeutic benefit of the drug. The existing literature suggests that the reduction in the IgE level is likely to result in a down-regulation of another IgE receptor, FcεRII/CD23. Because of the known immunomodulatory function of FcεRII, anti-IgE therapy may result in alterations of the immune system, in addition to simple absorption of IgE.