lymphatic system, systema lymphaticum - the interconnected system of spaces and vessels between body tissues and organs by which lymph circulates throughout the body

leucocyte, leukocyte, WBC, white blood cell, white blood corpuscle, white cell, white corpuscle - blood cells that engulf and digest bacteria and fungi; an important part of the body's defense system

B cell, B lymphocyte - a lymphocyte derived from bone marrow that provides humoral immunity; it recognizes free antigen molecules in solution and matures into plasma cells that secrete immunoglobulin (antibodies) that inactivate the antigens

T cell, T lymphocyte - a small lymphocyte developed in the thymus; it orchestrates the immune system's response to infected or malignant cells

lymphoblast - an immature lymphocyte

plasma cell, plasmacyte - a lymphocyte-like cell that develops from a B lymphocyte in reaction to a specific antigen; found in bone marrow and sometimes in the blood