IL9 and asthma: Collectively, these findings support a model in which the absolute IgE level is not determined by T2 status alone but by the net balance between IgE-promoting Th2/type 2 cytokines (IL-4 and IL-9) and IgE-antagonistic Th1 cytokines (IL-2 and IFN-γ), and they highlight serum cytokine profiling as a potential tool to distinguish qualitatively different high-IgE states in asthma.