(iii) In the amplification-of-mastocytosis phase, repeated food antigen ingestion induces the increase of CD4+TH2 cells, which provide the IL-4 signaling that induces MC progenitors to develop into MMC9s, which expand greatly after ingested antigens cross-link with MMC9 surface IgE/FcεR complex. This evidence concerns the gene CD4 and mastocytosis.