In human HAE, CD4+/CD25+ regulatory cells (Tregs) play a major role in regulating immune response and seem to be upregulated in the time course of the disease, which might be related to the suppression of the immune response to specific antigens and promotion of the secretion of anti-inflammatory cytokines like interleukin-10 (IL-10), transforming growth factor β (TGF- β), etc. (Vuitton et al., 2006). The gene discussed is IL10; the disease is hereditary angioedema.