Abstract
Mature B cells are grouped into two major subsets, B-1 and B-2, believed to derive from separate lineages. We have recently shown that B-1 cells, which are characterized by CD5 surface expression, specifically exhibit significant levels of the tyrosine kinase Lck in man. Here we show that also in mice Lck expression is restricted to B-1 cells and address the potential role of Lck in B-1 cell development and activation. Using as a model an Lck-/- mouse, we show that, while dispensable for B-1 cell development, Lck is required for full and sustained activation of the tyrosine phosphorylation and MAP kinase cascades triggered by the BCR in CD5+, B-1 cells. The data suggest a potential role for Lck in the achievement of the higher activation threshold required for productive BCR signaling in B-1 as compared to B-2 cells.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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B-Lymphocyte Subsets / cytology
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B-Lymphocyte Subsets / enzymology*
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B-Lymphocyte Subsets / immunology
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CD5 Antigens / analysis
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Lymphocyte Activation / physiology*
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / deficiency
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / genetics
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / physiology*
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MAP Kinase Signaling System / physiology
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Mice, Mutant Strains
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Peritoneal Cavity / cytology
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Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
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Phosphoric Monoester Hydrolases / deficiency
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Phosphorylation
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Protein Processing, Post-Translational / physiology
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Receptors, Antigen, B-Cell / immunology*
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Signal Transduction
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Specific Pathogen-Free Organisms
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Spleen / cytology
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Spleen / immunology
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ras Proteins / physiology
Substances
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CD5 Antigens
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Receptors, Antigen, B-Cell
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
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Phosphoric Monoester Hydrolases
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INPPL1 protein, human
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Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
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ras Proteins