LGL

LGL is an acronym that most often appears in a medical context to refer to large granular lymphocytes, a type of white blood cell involved in immune defense. LGLs are named for their relatively large size and the presence of azurophilic granules in their cytoplasm, which contain cytotoxic proteins used to kill infected or malignant cells. In humans, the major LGL subsets are cytotoxic T lymphocytes (CD3+ LGLs) and natural killer (NK) cells (CD3- LGLs). LGLs circulate in the blood and can expand in response to infections, inflammation, or immune stimulation.

In clinical practice, LGL leukemia describes a rare lymphoproliferative disorder characterized by a persistent increase in LGLs in the peripheral blood. This clonal or oligoclonal expansion can be associated with anemia, thrombocytopenia, recurrent infections, or autoimmune phenomena. Diagnosis typically involves a complete blood count with differential, examination of a peripheral blood smear, flow cytometry to determine LGL phenotype (often CD3+ TCR-bearing cells or CD3- NK cells), and molecular studies showing T-cell receptor gene rearrangements or NK cell markers. The disease often follows an indolent course, but some patients experience more symptomatic disease requiring treatment.

Treatment strategies focus on controlling symptoms and mitigating cytopenias or autoimmune features. Immunosuppressive therapies, such as methotrexate or cyclophosphamide, are commonly employed, and responses can be favorable with long-term management. Prognosis varies widely; many individuals have a stable course for years, while others may develop complications that require ongoing care.

LGL can also be used as an acronym in contexts outside medicine, referring to various organizations, products, or codes. The intended meaning is typically clarified by the surrounding context.