IMMUNOLOGY

Detailed explanation-1: -Type 1 T helper (Th1) cells produce interferon-gamma, interleukin (IL)-2, and tumour necrosis factor (TNF)-beta, which activate macrophages and are responsible for cell-mediated immunity and phagocyte-dependent protective responses.

Detailed explanation-2: -Role of IFN-gamma in Th1 differentiation: IFN-gamma regulates IL-18R alpha expression by preventing the negative effects of IL-4 and by inducing/maintaining IL-12 receptor beta 2 expression.

Detailed explanation-3: -Th1 cells secrete IFN-gamma, IL-2, IL-10, and TNF-alpha/beta. These cytokines promote macrophage activation, nitric oxide production, and cytotoxic T lymphocyte proliferation, leading to the phagocytosis and destruction of microbial pathogens.