Engaging CD19 or target of an antiproliferative antibody 1 on human B lymphocytes induces binding of B cells to the interfollicular stroma of human tonsils via integrin alpha 4/beta 1 and fibronectin.
Adhesion of B lymphocytes within the different compartments of secondary lymphoid organs is essential for the function of the humoral immune response. It is not currently known how the temporary immobilization of B cells in distinct areas of this complex microenvironment is regulated. The present study aimed at defining B cell antigens that initiate binding of B cells to human tonsil sections in situ. Engaging the B cell antigens CD19 and target of an antiproliferative antibody 1 (TAPA-1) with monoclonal antibodies induced adhesion of these B cells to the interfollicular stroma. This binding occurred through the integrin alpha 4 beta 1 on the B cell surface and via the extracellular matrix protein fibronectin expressed in the interfollicular compartment of the tonsil. Signaling through either antigen, CD19 or TAPA-1, depended on tyrosine kinases. Binding induced by engaging CD19 required an intact cytoskeleton, whereas TAPA-1-transmitted adhesion did not. We suggest that CD19 and TAPA-1 have a novel and unique function by regulating an alpha 4 beta 1/fibronectin-mediated binding of B cells to the interfollicular stroma of lymphoid tissues.
Behr
S
S
Department of Hematology and Oncology, Virchow University Hospital, Humboldt University Berlin, Germany.
Schriever
F
F
D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology / Q000502:physiology*; D018941:Antigens, CD19 / Q000276:immunology / Q000502:physiology*; D001402:B-Lymphocytes / Q000378:metabolism*; D002051:Burkitt Lymphoma; D002448:Cell Adhesion; D003239:Connective Tissue Cells; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping; D039041:Integrin alpha4beta1; D016023:Integrins / Q000378:metabolism*; D008565:Membrane Proteins; D014066:Palatine Tonsil / Q000166:cytology*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D015398:Signal Transduction; D060225:Tetraspanin 28; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018941:Antigens, CD19; C554798:CD81 protein, human; D005353:Fibronectins; D039041:Integrin alpha4beta1; D016023:Integrins; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D016201:Receptors, Lymphocyte Homing; D060225:Tetraspanin 28; D011494:Protein Kinases