IMMUNOLOGY

Detailed explanation-1: -TNF-, IL-1, and INF- are crucial for the expression of inflammatory mediators such as prostaglandins and leukotrienes and they induce the production of platelet-activating factor and IL-6. After stimulation by proinflammatory cytokines, Kuffer cells in the liver produce IL-6 and present it to the hepatocytes.

Detailed explanation-2: -IL-6 is a pleiotropic proinflammatory cytokine that is mainly secreted by monocytes.

Detailed explanation-3: -When macrophages are exposed to inflammatory stimuli, they secrete cytokines such as tumor necrosis factor (TNF), IL-1, IL-6, IL-8, and IL-12. Although monocytes and macrophages are the main sources of these cytokines, they are also produced by activated lymphocytes, endothelial cells, and fibroblasts.

Detailed explanation-4: -At steady state, IL-6 is produced by macrophages, dendritic cells, neutrophils, B cells and by some CD4+ T cells. In addition, IL-6 can also be secreted by endothelial cells, fibroblasts and epithelial cells (Figure 2).