The different T helper (Tʜ) cell subsets have a central function in initiation, programming, and regulation of the various protective and pathological antigen-specific immune responses. T helper 2 (Tʜ2) cells are involved in the immunity to helminthes and in the pathogenesis of allergy. They secrete specific cytokines such as IL-5, which stimulates eosinophil differentiation, and IL-13 and IL-4, which have effects on mucosal tissues and induce class switching of B cell towards immunoglobuline E production.
In vivo , naive T cell are instructed by dendritic cells and granulocytes towards Tʜ2 polarization through several signals including the presence of IL-4 and the absence of IL-12, a typical Tʜ1 signal.
In vitro , Tʜ2 cells can be generated from naive CD4 T cells upon primary activation via T cell receptor in the presence of IL-4. Addition of IL-2 enhances T cell proliferation. Tʜ2 polarization can be further promoted by the addition of an Anti-IFN-γ pure – functional grade antibody to block Tʜ1 polarization.
