The lymphatic system is a specialized part of the circulatory system. It differs from the circulatory system in that the lymphatics do not form a closed circuit like the circulatory system does. It begins in the intercellular spaces in the soft tissues.

It has three major goals and those are to maintain an internal fluid balance, absorb lipids from the intestines and transport them to the blood and immunity. It maintains fluid balance by collecting and maintaining interstitial fluid.

Lymphocytes are a major part of the lymphatic system. Lymphocytes are immune cells that protect the body from harmful things such as bacteria and viruses.

The lymphatic system is usually considered part of the circulatory system.

"The lymphatic system consists of organs, ducts, and nodes. It transports a watery clear fluid called lymph. This fluid distributes immune cells and other factors throughout the body. It also interacts with the blood circulatory system to drain fluid from cells and tissues."

The main function of the lymphatic system is to defend the body against diseases, absorb fats from the intestines and transport them to the blood, and to collect and return interstitial fluid, including plasma protein to the blood. 

The lymph organs are comprised of bone marrow, lymph nodes, spleen, and thymus.

The lymphatic system is a system of vessels that for the most part, are very close to the blood vessels.  They carry a fluid that cleans the tissues called lymph. Lymph is a lot like blood but it doesn't carry red blood cells or platelets.  It does carry food and oxygen to cells and picks up waste from cells. It also contains antigens, antibodies, and B cells that are an important part of your immune system; recognizing intruding disease germs, infection or bacteria and fighting them off.  Many viruses and bacteria are neutralized in this way. Most of the lymphatic fluid is circulated into the veins.  To answer your question, the lymphatic system works in conjunction with several systems, but is considered to be a specialized part of the circulatory system.