Expression of the T-cell-specific tyrosine kinase Lck in normal B-1 cells and in chronic lymphocytic leukemia B cells.
Src family kinases play a key role in mitogenesis. The exquisitely tissue-specific distribution of different Src family members suggests that a fine tuning of their expression might be a key prerequisite for cell homeostasis. We tested B cells from patients affected by B-cell chronic lymphocytic leukemia (B-CLL) for expression of Src family kinases. The T-cell-specific tyrosine kinase Lck was found to be expressed at significant levels in CLL B-cells. This finding could be accounted for either by ectopic expression of Lck in B-CLL or by specific expression of this kinase in normal B-1 cells, which are believed to be the normal counterpart of CLL B cells. To answer this question B cells from different sources, characterized by a different size of the B-1 subpopulation, were tested for Lck expression. The results show that Lck expression is a feature of CD5(+), B-1 cells, suggesting a potential role for Lck in the self-renewal capacity of this B-cell subpopulation and supporting the notion that B-1 cells are the subset undergoing oncogenic transformation in B-CLL. Furthermore, we show that the CD5(-), B-2 subpopulation, while normally lacking Lck expression, acquires the capacity to express Lck ectopically upon transformation by EBV.
Majolini
M B
MB
Department of Evolutionary Biology, University of Siena, Siena, Italy.
D'Elios
M M
MM
Galieni
P
P
Boncristiano
M
M
Lauria
F
F
Del Prete
G
G
Telford
J L
JL
Baldari
C T
CT
D016175:B-Lymphocyte Subsets / Q000201:enzymology*; D015153:Blotting, Western; D018956:CD5 Antigens / Q000032:analysis; D002472:Cell Transformation, Viral; D004854:Herpesvirus 4, Human; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000201:enzymology*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D013601:T-Lymphocytes / Q000201:enzymology; D014407:Tumor Cells, Cultured / Q000201:enzymology
D018956:CD5 Antigens; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010751:Phosphopyruvate Hydratase