Activation of human B cells through the CD19 surface antigen results in homotypic adhesion by LFA-1-dependent and -independent mechanisms.
Addition of CD19 monoclonal antibodies (mAb) to highly purified tonsillar B cells resulted in homotypic adhesion and the formation of cell clusters. This response was completely blocked by antibody to LFA-1, indicating an LFA-1-dependent adhesion mechanism. In contrast, aggregate formation by B cells activated with phorbol myristate acetate (PMA) was only partially inhibited by anti-LFA-1 antibody, and those formed in response to PMA plus CD19 antibody were not inhibited at all, suggesting aggregation of activated B cells stimulated with CD19 antibody was LFA-1 independent. This was confirmed with B-cell lines. The pre-B-cell line Nalm-6 formed aggregates in response to CD19 antibody which were not inhibited with anti-LFA-1. In addition, CD19 antibody induced aggregate formation by an Epstein-Barr virus (EBV)-transformed B-cell line derived from an LFA-1-deficient donor. These results suggest that different adhesion molecules may operate at different stages of B-cell activation, and that CD19 may be important in cell-cell interactions involved in regulation of antibody responses.
Smith
S H
SH
Dept. of Immunology, Institute of Child Health, London, U.K.
Rigley
K P
KP
Callard
R E
RE
D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology*; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D002449:Cell Aggregation / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000276:immunology*; D014066:Palatine Tonsil / Q000276:immunology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte; D016169:Lymphocyte Function-Associated Antigen-1