Now let's suppose our antigen is picked up by the macrophage. What the macrophage will do is it will display that antigen bound to a special type of protein complex on the membrane of the macrophage. And the protein complex is known as the major histocompatibility class two complex. And this is shown in this diagram. Now anytime we have an antigen in our body either actually floating around in our body or bound to some other type of leukocide we're going to have a specific B lymphocide that has the B cell receptors that can bind to that particular and that specific pathogenic antigen. So the B lymphocyte can either pick up these antigens found floating around our system or it can actually also grab the antigen off of our macrophage or some other type of leukocytes.