#study Immunology-Serology Difficult MCQs Round 2 R A T I O N A L E : 1. IL-12 is a key cytokine produced by antigen-presenting cells, such as dendritic cells and macrophages, that promotes the differentiation of naive T-helper (Th0) cells into Th1 cells. This process is crucial for initiating a cell-mediated immune response. 2. The CH50 (total complement hemolytic activity) assay measures the functional activity of the classical complement pathway by quantifying the ability of serum to lyse ant