TCL1 (MRQ-7)

T-cell leukemia/lymphoma protein 1 (TCL1, TCL1A, p14TCL1) is a 14 kDa product of the TCL1 gene that is involved in T-cell prolymphocytic leukemia (T-PLL). TCL1 protein is normally found in the nucleus and cytoplasm of lymphoid lineage cells during early embryogenesis. Chromosomal translocations may lead to overexpression of TCL1, resulting in T-cell leukemia and B-cell lymphoma. TCL1 binds to a novel site in the pleckstrin homology (PH) domain, resulting in activation and nuclear translocation of Akt by overexpressed TCL1 which may promote an anti-apoptotic response; this may normally serve to promote growth during development but may lead to malignancy when TCL1 is overexpressed. TCL1 is expressed in differentiated B-cells under both reactive and neoplastic conditions, antigen committed B-cells, and in germinal center B-cells. TCL1 is down-regulated in the latest stage of B-cell differentiation. TCL1 is overexpressed in Burkitt lymphoma, the majority of AIDS-related non-Hodgkin lymphoma-designated immunoblastic plasmacytoid lymphoma, lymphoblastic lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, diffuse large B-cell lymphoma, and primary cutaneous B-cell lymphoma. Therefore, the most useful application of anti-TCL1 is the discrimination of B-cell lymphomas from T-cell lymphomas, CD30+ anaplastic large cell lymphomas, multiple myeloma, and marginal zone B-cell lymphoma.