The immune system fights off the pathogen by Leukocytes also known as white blood cells. When a pathogen enters the body the immune system becomes alert to it and sends out sends out the Phagocytes (a type of Leukocytes) which engulfs the pathogens.
The first one: Saturated fats
Second one: unsaturated fat
Third one: lipoprotein
Fourth one: cholesterol
(Second and fourth one not sure)