lymphocytic

Lymphocytic is an adjective relating to lymphocytes, a type of white blood cell central to the immune system. Lymphocytes circulate in blood and reside in lymphoid tissues, including lymph nodes, the spleen, and mucosal surfaces.

Lymphocytes arise from hematopoietic stem cells in the bone marrow. B cells mature in the bone marrow; T cells mature in the thymus; natural killer (NK) cells originate from the common lymphoid progenitor. B cells mediate humoral immunity through antibody production; T cells perform cell-mediated responses (cytotoxic and helper roles) and regulate immune reactions; NK cells provide rapid cytotoxic responses against infected or transformed cells.

In pathology, the term is used to describe cells, infiltrates, or processes dominated by lymphocytes. Laboratory terms include lymphocytosis (elevated lymphocyte count) and lymphocytopenia (reduced count). Lymphocytosis frequently accompanies viral infections (such as EBV or CMV), some bacterial infections, and certain leukemias. Lymphocytopenia can result from acute infections, advanced HIV infection, malnutrition, corticosteroid or cytotoxic therapy, or bone marrow failure.

Lymphoid neoplasms include acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL), which arise from malignant lymphocytes, as well as lymphomas that involve lymphocytes in nodal or extranodal sites. Lymphocytic infiltration refers to accumulation of lymphocytes in tissues and occurs in various autoimmune diseases (for example Hashimoto thyroiditis) and chronic inflammatory conditions.

Etymology: from lymph, the clear fluid circulating in the lymphatic system, plus cyte meaning cell.