- Th-1 cytokines such as Gamma Interferon (IFN), Interleukin-2 (IL-2) and Tumour Necrosis Factor-beta (TNF-ß). Th1 cytokines promote production of opsonizing antibodies (e.g., IgG1) and induction of cellular cytotoxicity and macrophage activation. Th1 responses are prominent in the defence against pathogens which replicate intracellularly.