However, by three minutes, the constriction sets in, which peaks at around 10–15 minutes, and usually resolves itself by an hour. During an episode of this type of bronchoconstriction, the levels of inflammatory mediators, particularly leukotrienes, histamine, and interleukin, increase. TH2-type lymphocytes are activated, with an increase in T cells expressing CD25 (IL-2R), and B cells expressing CD 23, causing increased production of IgE.