Document Detail

Role of the B cell antigen receptor in antigen processing and presentation. Involvement of the transmembrane region in intracellular trafficking of receptor/ligand complexes.
MedLine Citation:
PMID:  8245457     Owner:  NLM     Status:  MEDLINE    
To study the role of the B cell Ag receptor (membrane-bound Ig [mIg]) in Ag processing and presentation, we have generated several Ig transfectants that express transfected TEPC-15 idiotype (T15-Id) mIgM with phosphorylcholine (PC)-binding specificity. The wild-type Ig transfectant is able to present a specific Ag (e.g., PC-conjugated hen egg-white lysozyme [PC-HEL]) more efficiently than a nonspecific Ag (HEL) to a T cell hybridoma recognizing an epitope on the HEL molecule. A substitution in the entire spacer, transmembrane, and cytoplasmic region of mIg with an equivalent region of I-A alpha chain completely abolishes this mIg-enhanced Ag presentation. Experiments with the wild-type and substituted variant Ig transfectants suggest that this substitution may interfere with normal intracellular trafficking of mIg after cross-linking with specific Ag or antibodies specific for the mIg (anti-T15-Id mAb). Prolonged treatment of the wild-type Ig transfectants with specific Ag or anti-T15-Id mAb reduces the surface expression of T15-Id mIgM and leads to an accumulation of T15-Id mIgM inside the cells. The reduced surface expression and the elevated cytoplasmic accumulation of T15-Id mIgM are not observed in the variant Ig transfectant. Despite the ability of the variant to endocytose ligands similarly to the wild-type Ig transfectant, this variant displays a higher rate of recycling of the mIg/ligand complexes back to the cell surface and a lower rate of degradation of the ligands. These abnormalities may be responsible for the deficiency in mIg-mediated enhancement of Ag presentation in the variant Ig transfectant. Therefore, our results suggest that the transmembrane region of mIg is involved in intracellular trafficking of receptor/ligand complexes and that proper delivery and handling of internalized Ag are required for the enhanced presentation of specific Ag by B cells.
K J Liu; V S Parikh; P W Tucker; B S Kim
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  151     ISSN:  0022-1767     ISO Abbreviation:  J. Immunol.     Publication Date:  1993 Dec 
Date Detail:
Created Date:  1994-01-06     Completed Date:  1994-01-06     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  6143-54     Citation Subset:  AIM; IM    
Department of Microbiology-Immunology, Northwestern University Medical School, Chicago, IL 60611.
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MeSH Terms
Amino Acid Sequence
Antibodies, Monoclonal / immunology
Antigen Presentation*
Cell Line
Immunoglobulin Idiotypes / analysis
Immunoglobulin M / analysis,  metabolism*
Mice, Inbred BALB C
Molecular Sequence Data
Receptors, Antigen, B-Cell / analysis,  metabolism*,  physiology*
Grant Support
Reg. No./Substance:
0/Antibodies, Monoclonal; 0/Immunoglobulin Idiotypes; 0/Immunoglobulin M; 0/Receptors, Antigen, B-Cell

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