ACAAI Board Practice Exam 2025 – Complete Prep Resource

Tuberculosis-infected macrophages play a crucial role in the immune response by secreting specific cytokines that are essential for the differentiation of T-helper 1 (Th1) cells. The correct answer identifies the cytokines IL-12, IL-18, and IL-23, which are pivotal in promoting the Th1 response.

IL-12 is particularly important as it activates T-cells and enhances their production of interferon-gamma (IFN-γ), a key cytokine produced by Th1 cells that further enhances macrophage activation to kill intracellular pathogens like Mycobacterium tuberculosis. IL-18 also supports this process by promoting the production of IFN-γ by T cells. IL-23 is involved in the maintenance and proliferation of Th17 cells, but it also has implications in the overall inflammatory response which supports the Th1 differentiation indirectly.

This combination of cytokines creates a favorable immune environment for the body to mount a strong Th1 response, critical for controlling tuberculosis infection. The secretion of these cytokines by macrophages in response to the pathogen helps to ensure that there is adequate differentiation and function of the T-helper cells necessary to combat infection effectively.

The other combinations of cytokines listed in the choices, while involved in immune