IgE-dependent antigen focusing by human B lymphocytes is mediated by the low-affinity receptor for IgE.
In this study we investigated the role of the low-affinity receptor for IgE (Fc epsilon RII, CD23) on Epstein-Barr virus (EBV)-transformed human B cells in the uptake and presentation to T cells of antigen after complexing with IgE. Cloned EBV-transformed B cells were incubated for 5 h with (4-hydroxy-3-iodo-5-nitrophenyl)acetyl (NIP)-haptenized tetanus toxoid (NIP-TT) or NIP-TT complexed with a chimeric human IgE/mouse anti-NIP monoclonal antibody (IgE x NIP-TT) and then contacted for 2 min with autologous cloned TT-specific T cells. Intracellular Ca2+ mobilization in T cells was determined as an early indicator of T cell activation. The antigen-presenting capacity of B cells was significantly increased by complexing the antigen with IgE. This effect could be selectively reversed in a dose-dependent manner by blocking the Fc epsilon RII with an anti-CD23 monoclonal antibody. The IgE-mediated increased capacity for presenting antigen became particularly evident when B cells were incubated with NIP-TT or IgE x NIP-TT for only 1 h at 4 degrees C, washed and then cultivated for 6 h at 37 degrees C allowing uptake and processing of the antigen. These results indicate a new role of the Fc epsilon RII/CD23 molecules in the uptake of antigen by APC which might be of importance in the maintenance of an ongoing immune response against allergens.
Pirron
U
U
Institute for Immunology, University of Munich, FRG.
Schlunck
T
T
Prinz
J C
JC
Rieber
E P
EP
D000938:Antigen-Presenting Cells / Q000502:physiology*; D000941:Antigens / Q000378:metabolism; D000944:Antigens, Differentiation, B-Lymphocyte / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology*; D002461:Cell Line, Transformed; D003432:Cross-Linking Reagents; D006241:Haptens / Q000276:immunology; D004854:Herpesvirus 4, Human; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism / Q000502:physiology*; D011961:Receptors, Fc / Q000502:physiology*; D017455:Receptors, IgE; D013745:Tetanus Toxoid / Q000276:immunology
D000941:Antigens; D000944:Antigens, Differentiation, B-Lymphocyte; D003432:Cross-Linking Reagents; D006241:Haptens; D011961:Receptors, Fc; D017455:Receptors, IgE; D013745:Tetanus Toxoid; D007073:Immunoglobulin E