Abstract
At least two membrane receptors have been defined through which human T lymphocytes can be induced to proliferate and differentiate, namely the CD3-Ti antigen receptor complex and the CD2 molecule. Monoclonal antibodies directed at either CD2 or CD3 induce intracellular second messenger production and subsequent protein phosphorylation. On most human non-B lymphocytes, CD3-Ti and CD2 are coexpressed and seem to be functionally interrelated. But there are minor subpopulations in which these receptor systems can transduce signals despite a mutually exclusive expression, indicating that CD3-Ti and CD2 can act independently of each other. This view is supported by the finding that most monoclonal antibodies directed at the CD45 molecules are strongly co-mitogenic with CD2 but not CD3 monoclonal antibodies. As the intracytoplasmic domains of CD45 have tyrosine phosphatase activity these functional effects could be explained by a physical association between CD2 and CD45. Using chemical crosslinking techniques, we now show that CD45 is linked to CD2 on the surface of human T lymphocytes.
MeSH terms
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Antibodies, Monoclonal / pharmacology
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Antigens, CD / immunology*
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Antigens, Differentiation / immunology*
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Antigens, Differentiation, T-Lymphocyte / immunology*
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CD2 Antigens
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CD3 Complex
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Cross-Linking Reagents / pharmacology
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Enzyme-Linked Immunosorbent Assay
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Histocompatibility Antigens / immunology*
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Histocompatibility Antigens Class I / immunology
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Humans
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Immunosorbent Techniques
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Leukocyte Common Antigens
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Molecular Weight
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Peptide Fragments
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Phosphoprotein Phosphatases / metabolism
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Phosphoproteins / metabolism
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Phosphorylation
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Protein Tyrosine Phosphatases
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Receptors, Antigen, T-Cell / immunology
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Receptors, Immunologic / immunology*
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Second Messenger Systems
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Serine Endopeptidases
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Succinimides / pharmacology
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T-Lymphocytes / immunology*
Substances
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Antibodies, Monoclonal
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Antigens, CD
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Antigens, Differentiation
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Antigens, Differentiation, T-Lymphocyte
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CD2 Antigens
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CD3 Complex
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Cross-Linking Reagents
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Histocompatibility Antigens
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Histocompatibility Antigens Class I
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Peptide Fragments
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Phosphoproteins
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Receptors, Antigen, T-Cell
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Receptors, Immunologic
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Succinimides
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Phosphoprotein Phosphatases
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Leukocyte Common Antigens
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Protein Tyrosine Phosphatases
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Serine Endopeptidases
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glutamyl endopeptidase
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dithiobis(succinimidylpropionate)