Which statement is true about IL-12?

Which statement is true about IL-12?

• A. It promotes Th2 differentiation
• B. It inhibits NK cell activity
• C. It promotes differentiation toward the Th1 subset
• D. It is primarily produced by B cells

Answer: (C)

IL-12 is a cytokine that pushes the immune response toward a cell-mediated, Th1-type profile. It is produced by antigen-presenting cells such as macrophages and dendritic cells, not by B cells. Its key action is to drive differentiation of naive CD4+ T cells into Th1 cells, a lineage that supports responses against intracellular pathogens and activates macrophages. IL-12 also stimulates NK cells to produce IFN-γ, enhancing cytotoxic and macrophage-activating activities. This makes the statement about promoting differentiation toward the Th1 subset the correct one. IL-12 does not promote Th2 differentiation (that role is more associated with IL-4), and it does not inhibit NK cell activity (it enhances NK cell function). It’s not primarily produced by B cells, but by macrophages and dendritic cells.

IL-12 is a cytokine that pushes the immune response toward a cell-mediated, Th1-type profile. It is produced by antigen-presenting cells such as macrophages and dendritic cells, not by B cells. Its key action is to drive differentiation of naive CD4+ T cells into Th1 cells, a lineage that supports responses against intracellular pathogens and activates macrophages. IL-12 also stimulates NK cells to produce IFN-γ, enhancing cytotoxic and macrophage-activating activities.

This makes the statement about promoting differentiation toward the Th1 subset the correct one. IL-12 does not promote Th2 differentiation (that role is more associated with IL-4), and it does not inhibit NK cell activity (it enhances NK cell function). It’s not primarily produced by B cells, but by macrophages and dendritic cells.