Major group of blood cells that carry no blood pigment (haemoglobin). Leukocytes (white blood cells) are responsible for very different functions in the human immune system. They are produced in the human bone marrow. See also: Erythrocytes
The lymphatic system is a complex system of lymphoid organs (thymus, bone marrow, lymph nodes, spleen, etc.) and the thin-walled lymphatic system. This system produces and transports lymphatic fluid. The lymphatic system is part of the immune system. See also: Lymphocytes
Subgroup of leukocytes. Their main task is the targeted defence against infectious agents. Lymphocytes are also active against modified endogenous cells (e.g. tumour cells). A distinction is made between the subgroup of T and B lymphocytes that mature after their formation in the bone marrow in the thymus or bone marrow and are jointly responsible for the acquired immune response.