The number of antibodies in his blood stream has increased because the plasma cell is specialized in producing a specific protein, called an antibody, that will respond to the same antigen that matched the B cell receptor (searches for antigen matching its receptors).
Antibodies are released from the plasma cell so that they can seek out intruders and help destroy them. Plasma cells produce antibodies at an amazing rate and can release tens of thousands of antibodies per second.
The lymphatic system can be thought of as a drainage system needed because, as blood circulates through the body, blood plasma leaks into tissues through the thin walls of the capillaries.
Learn more about the lymphatic system and the vital role it plays in keeping the cardiovascular system working at Study.com.