BCL-6 protein is expressed in precursor T-cell lymphoblastic lymphoma and in prenatal and postnatal thymus.

TitleBCL-6 protein is expressed in precursor T-cell lymphoblastic lymphoma and in prenatal and postnatal thymus.
Publication TypeJournal Article
Year of Publication2001
AuthorsHyjek E, Chadburn A, Liu YF, Cesarman E, Knowles DM
Date Published2001 Jan 01
KeywordsAdolescent, Adult, Apoptosis, bcl-X Protein, Child, Child, Preschool, DNA-Binding Proteins, Female, Fetus, Humans, Immunophenotyping, Infant, Infant, Newborn, Lymphoma, Follicular, Lymphoma, T-Cell, Male, Middle Aged, Precursor Cell Lymphoblastic Leukemia-Lymphoma, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Proto-Oncogene Proteins c-bcl-6, Thymus Gland, Transcription Factors

The organization and expression of the BCL-6 gene in normal and neoplastic thymic T cells has not been fully determined. We examined 8 precursor T-cell lymphoblastic lymphomas (T-LBLs) and found significant BCL-6 expression in 4 cases. Three of the BCL-6(+) cases expressed a common thymocyte phenotype (CD4(+), CD8(+)), and one expressed a precursor thymocyte phenotype (CD4(-), CD8(-)). In 6 cases evaluated, including those expressing BCL-6, molecular analyses demonstrated a germline configuration of the BCL-6 gene and a wild-type BCL-6 gene first exon-intron boundary region. We also evaluated 12 normal prenatal and postnatal thymuses for BCL-6 protein. BCL-6 was expressed by most cortical thymocytes and by scattered medullary thymocytes. BCL-6(+) cortical and medullary thymocytes also expressed CD2, CD3, CD4, CD5, CD7, or CD8. We further analyzed the pattern of BCL-2 and BCL-X(L) expression and their coexpression with BCL-6 in normal thymus and T-LBL and compared it to that of follicle centers of reactive lymph nodes and follicular lymphoma. BCL-6(+) cortical thymocytes coexpressed BCL-X(L) but not BCL-2. All 4 BCL-6(+) T-LBLs and 4 BCL-6(-) T-LBLs coexpressed BCL-2 and BCL-X(L). Conceivably, T-LBLs may arise through clonal expansion of cortical thymocytes normally expressing the BCL-6 protein. The pattern of BCL-6, BCL-2, and BCL-X(L) expression in cortical thymocytes is highly reminiscent of germinal centers, and the abnormal coexpression of BCL-2, BCL-X(L), and BCL-6 in T-LBL is analogous to coexpression in follicle center cell lymphomas, suggesting that coexpression of these anti-apoptotic genes may contribute to the pathogenesis of T-LBL.

Alternate JournalBlood
PubMed ID11133771
Related Faculty: 
Amy Chadburn, M.D. Ethel Cesarman, M.D., Ph.D.

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