Characterization of H4: a mouse T lymphocyte activation molecule functionally associated with the CD3/T cell receptor.
The monoclonal antibody C398.4A was produced by immunizing Armenian hamsters with the mouse T cell clone D10.G4.1. It recognizes a molecule selectively expressed by activated mouse T cells and was named H4. H4 is expressed on the T cell surface about 24 h after activation and peaks at day 7. By contrast, it is not expressed by resting or activated B cells, macrophages, or fibroblasts. It is also expressed by CD4 or CD8 single-positive mature thymocytes. Immunoprecipitation showed that H4 is a disulfide-linked dimer, precipitating as a broad band at about 50-65 kDa under nonreducing conditions and at 25 and 29 kDa under reducing conditions. Deglycosylation of the reduced H4 by N-glycanase gave rise to a single band of about 21 kDa, suggesting that the two chains may be differentially glycosylated forms of the same protein. The H4 expression pattern and biochemical features, together with cross-blocking, co-capping, co-modulation, and immunoprecipitation preclearing experiments showed that H4 is different from other known co-stimulatory molecules such as CD69, CD2, Ly-6, CD25, OX-40, Mac-1 and LFA-1. By in vitro kinase assay, H4 was found to co-precipitate a tyrosine kinase activity that phosphorylated substrates of about 29 and 25 kDa. Co-modulation and co-capping experiments showed that H4 is physically associated with the CD3/T cell receptor. These data suggest that H4 may function as a T cell-specific co-stimulatory molecule and play a role in the T cell response when the activation stimulus is limited either because the antigen is only available in low concentration or has a low agonistic activity.
Redoglia
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V
Divisione Universitaria di Ematologia, Dipartimento di Medicina e Oncologia Sperimentale, Università di Torino, Italy.
Dianzani
U
U
Rojo
J M
JM
Portolés
P
P
Bragardo
M
M
Wolff
H
H
Buonfiglio
D
D
Bonissoni
S
S
Janeway
C A
CA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D016130:Immunophenotyping; D008213:Lymphocyte Activation; D051379:Mice; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000276:immunology; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011505:Protein-Tyrosine Kinases