Class switch recombination to IgG, IgA, and IgE is promoted by cytokines produced by helper T cells.

Class switch recombination to IgG, IgA, and IgE is promoted by cytokines produced by helper T cells.

• A. IL-2 and IL-7
• B. Cytokines from helper T cells, such as IL-4 and IFN-γ
• C. IL-10 and TGF-β
• D. TNF-α and IL-6

Answer: (B)

Class switch recombination is directed by signals from helper T cells. When a B cell is activated, interaction with a helper T cell through CD40-CD40L, together with cytokines the T cell releases, directs which constant region the B cell will switch to. IL-4 from Th2 cells promotes switching toward IgE (and certain IgG subclasses), while IFN-γ from Th1 cells promotes switching toward other IgG subclasses. TGF-β is important for IgA switching in mucosal settings. The idea that cytokines produced by helper T cells guide CSR to IgG, IgA, and IgE reflects how the immune system tailors antibody effector functions, making this statement the best description.

Class switch recombination is directed by signals from helper T cells. When a B cell is activated, interaction with a helper T cell through CD40-CD40L, together with cytokines the T cell releases, directs which constant region the B cell will switch to. IL-4 from Th2 cells promotes switching toward IgE (and certain IgG subclasses), while IFN-γ from Th1 cells promotes switching toward other IgG subclasses. TGF-β is important for IgA switching in mucosal settings. The idea that cytokines produced by helper T cells guide CSR to IgG, IgA, and IgE reflects how the immune system tailors antibody effector functions, making this statement the best description.