Document Detail


Medullary thymic epithelium expresses a ligand for CTLA4 in situ and in vitro.
MedLine Citation:
PMID:  8395547     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A fusion protein consisting of the extracellular domain of CTLA4 and an Ig C gamma 1 chain (CTLA4-Ig) was used to examine the distribution of the ligands for CTLA4 within the murine thymus and to characterize the nature of these ligands. Two-color immunofluorescence of thymus tissue revealed binding of the fusion protein to medullary thymic epithelial cells and dendritic cells within the corticomedullary and medullary areas of the thymus. Medullary cells binding the fusion protein also expressed MHC class II products and ICAM-1. Thymus tissue sections treated with cross-linking fixatives, such as glutaraldehyde, paraformaldehyde, or 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide no longer bound the CTLA4 fusion protein, indicating that binding was very sensitive to the tertiary structure of the tissue ligand. The ability of thymic tissue to bind the fusion protein was developmentally regulated. At day 14 of gestation, only scattered single cells were labeled. Clusters of labeled cells, which were detected by day 16 of gestation, increased in frequency with advancing gestational age. Consistent with the in situ labeling studies, CTLA4-Ig also labeled several thymic epithelial cell lines previously shown to have a medullary phenotype. Polymerase chain reaction analysis of mRNA extracted from these cells indicated they contained mRNA for B7, a known counter receptor for CTLA4 and CD28. Immunoprecipitation of 125I-labeled thymic epithelial cells with the CTLA4-Ig detected a M(r) 65,000 to 70,000 species under reducing conditions, consistent with previous studies of B7. These data suggest that the ligand for CTLA4 expressed by thymic epithelial cells in vitro is B7 and that the expression of this ligand in situ is largely restricted to the medullary compartment and is associated with epithelial cells and dendritic cells.
Authors:
A J Nelson; S Hosier; W Brady; P S Linsley; A G Farr
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; 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 Sep 
Date Detail:
Created Date:  1993-09-28     Completed Date:  1993-09-28     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2453-61     Citation Subset:  AIM; IM    
Affiliation:
Department of Biological Structure, University of Washington, Seattle 98195.
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MeSH Terms
Descriptor/Qualifier:
Animals
Antigens, CD / physiology
Antigens, CD28
Antigens, Differentiation / metabolism*
Antigens, Differentiation, T-Lymphocyte / physiology
Base Sequence
Cell Line
Epithelium / metabolism
Female
Flow Cytometry
Immunoconjugates*
Ligands
Male
Mice
Mice, Inbred BALB C
Molecular Sequence Data
Polymerase Chain Reaction
Recombinant Fusion Proteins / metabolism
Thymus Gland / metabolism*
Grant Support
ID/Acronym/Agency:
AG04360/AG/NIA NIH HHS; AI24137/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Antigens, CD; 0/Antigens, CD28; 0/Antigens, Differentiation; 0/Antigens, Differentiation, T-Lymphocyte; 0/Immunoconjugates; 0/Ligands; 0/Recombinant Fusion Proteins; 0/abatacept; 0/cytotoxic T-lymphocyte antigen 4

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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