This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
IL-1 is secreted from which cells 
Select and explain. 
A. Mast cells, B. Eosinophils, C. Macrophages, D. Neutrophils
C: Macrophages
Answer: C: Macrophages 
Explanation: Tumor necrosis factor (TNF)Interleukin-1 (IL-1)Granulocyte-monocyte colony-stimulating factor (GM-CSF)Granulocyte colony-stimulating factor (G-CSF)Monocyte colony-stimulating factor (M-CSF)These factors are formed by activated macrophage cells in the inflamed tissues and in smaller quantities by other inflamed tissue cells.Ref: Guyton and Hall textbook of medical physiology 13th edition. Page:462