1.produce antibodies , kill virus and bacteria
2.form macrophage ,cells eating(eat whatever substances in blood except RBC
3.produce histamines that involved in allergic response
4.and also produce heparin to prevent blood clotting when blood flowing with lower speed.
5.cells eating,eat the bacteria and dead cells or tissues that due to wound
6.reduce the allergic symptoms in another way to defend against parasitic infestations.