Characterization of novel costimulatory molecules. A protein of 38-42 kDa from B cell surface is concerned with T cell activation and differentiation.
Optimal activation of T cells often requires signals delivered by the ligation of T cell receptor (TcR) and those resulting from costimulatory interaction between certain T cell surface accessory molecules and their respective counter receptors on antigen presenting cells. The molecular events underlying the co-stimulatory activity are still not understood fully. Here we describe a 38-42-kDa (B3) protein, present on the surface of lipopolysaccharide-activated B cells, which can provide co-stimulation to resting T cells leading to a predominant release of interleukin (IL)-4 and IL-5 and negligible amounts of IL-2 and interferon-gamma. Binding assay and electron microscopic autoradiography data suggest that this molecule binds T cells, and the same can be competed by unlabeled B3. Characterization experiments point out that B3 shows up as a single prominent peak on reverse phase-high performance liquid chromatography, runs as a single spot in reducing two-dimensional gel electrophoresis, and is a phosphoglycoprotein. The Western analysis indicate that it does not cross-react with antibodies directed against murine ICAM-1, LFA-1 alpha, VCAM-1, HSA, and B7 suggesting the novelty of the protein. The internal amino acid sequence of this molecule suggests that it does not belong to a known category of murine B cell surface molecules.
Vinay
D S
DS
Institute of Microbial Technology, Chandigarh, India.
Raje
M
M
Verma
R K
RK
Mishra
G C
GC
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D008081:Liposomes; D008213:Lymphocyte Activation / Q000502:physiology*; D008222:Lymphokines / Q000096:biosynthesis; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
D008070:Lipopolysaccharides; D008081:Liposomes; D008222:Lymphokines; D008565:Membrane Proteins