What Type Of Cells Help Defend The Body?

There are many types of cells that help defend the body. Take the epithelial cells on our skin for instance. They form a barrier against our internal body and the external environment and thus help to reduce our body's exposure to germs.
However, the most credit for body defense goes to the white blood cells that form up our body's immune system. These are also known as leukocytes. They can be broadly categorized as granulocytes or agranulocytes depending on whether they have granules in them or not. Granulocytes include neutrophils, basophils and eosinophils. Agranulocytes (those without granules) include lymphocytes, monocytes and macrphages.
They either take up the foreign body and digest it, thereby destroying it (for example macrphages), or they produce antibodies that attach to the pathogen (bacteria or virus) and kill it (for example lymphocytes).