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
JournalBlood
Volume97
Issue1
Pagination270-6
Date Published2001 Jan 01
ISSN0006-4971
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
Abstract

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.

DOI10.1182/blood.v97.1.270
Alternate JournalBlood
PubMed ID11133771
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Amy Chadburn, M.D. Ethel Cesarman, M.D., Ph.D.

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