If you cut your knee, pus, which is caused by may form. medicinal material excreted by macrophages the death of macrophages pathogens trying to infect the area blood cells losing their hemoglobin

If you cut your knee, pus, which is caused by death of macrophages, may form.

Explanation:

    When microbes invade your body, white blood cells, which specialize in the body's defense, circulate in your blood. Macrophages and neutrophils (two types of white blood cells) eliminate most invaders by swallowing them in a process called phagocytosis. Already lymphocytes (T cells) act as artillery. They bombard the enemy from afar. When they identify a foreign protein - the invader antigen -, another type of lymphocyte (B-cell) releases antibodies that are designed to kill or immobilize a specific microorganism. The pus is formed by the "corpses" of battle - the white blood cells that died to defend you, mixed with dead invading microbes. When the fight is very fierce, macrophages release substances that stimulate the brain region in charge of body temperature, causing fever. It is a kind of red alert for the body to mobilize all resources against aggression. As difficult as combat is, the immune system never surrenders.