What is large granular lymphocytic leukaemia (LGLL)?

Large granular lymphocytic leukaemia (LGLL) is a rare blood cancer. It is made up of the white blood cells in your blood called lymphocytes. Lymphocytes work as part of the body’s immune response. Lymphocytes are created in the bone marrow, but are also found in the blood and the immune system.

In LGLL there is an excess number of large granular lymphocytes.

• T-lymphocytes (T-cells)
• Natural killer‑lymphocytes (NK-cells)

There are also three subtypes of LGLL:

• Chronic T-cell LGLL, which is present in 85% of LGLL patients and most common in those over 60. More information can be found here.
• NK-cell LGLL is present in 10% of patients. More information can be found here.
• Aggressive NK-cell LGLL, is present in 5% of LGLL patients and on average found in those aged 40. More information on this type of LGLL can be found here.

In Europe, the incidence of LGLL is 0.2-0.72 cases per million people each year. This equates to between 14 and 50 people a year in the UK and occurs in both men and women.

The cause of LGLL is unknown, but it is not related to anything that you have done. Research work is ongoing to better understand the cause.

Transformation of chronic LGLL into aggressive LGLL is also extremely rare.

A mutation is a change in one or more of the patients’ genes, often known as the building blocks of DNA. These mutations cannot be inherited and passed down to your future children.

Mutated genes in LGLL are :

• Signal Transducer and Activator of Transcription 3 (STAT3). Found in 30-40% of LGLL patients
• Tumour Necrosis Factor Alpha–Induced Protein 3 (TNFAIP3): Present in 8% of patients
• Signal Transducer and Activator of Transcription 5B (STAT5B). Found in 2% of patients. This gene is found in aggressive NK-LGLL, although the above two genes have been also found.

15% to 40% of LGLL patients also have an autoimmune disease.

LGLL is also linked with other diseases that involve B-cells. This includes chronic lymphocytic leukaemia (CLL), follicular lymphoma, and mantle cell lymphoma.