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We used a sensitive in vitro culture system to follow, in embryonic blood, the number and state of commitment of B cell precursors along ontogeny. We describe a wave of circulating multipotent progenitors, first detectable at day 10 of gestation, and reaching a maximum in absolute numbers at day 12. They are undetectable by day 14 of gestation, when committed B cell precursors can be detected in fetal...
We address the mechanism of hybrid resistance (HR) in vitro using NK effector cells and target lymphoblasts from H-2 b , H-2 d , and H-2 b/d mice. The 5E6 (Ly49C) + subset of F1 NK cells lyse BALB/c (H-2 d ) but not B6 (H-2 b ) targets unless either anti-5E6 or anti-H-2K b MAbs are present. H-2D d transgenic B6 (D8) targets are not susceptible...
Mature T cells comprise two mutually exclusive lineages expressing heterodimeric αβ or γδ antigen receptors. During development, β, γ, and δ genes rearrange before α, and mature γδ cells arise in the thymus prior to αβ cells. The mechanism underlying commitment of immature T cells to the αβ or γδ lineage is controversial. Since the δ locus is located within the α locus, rearrangement of α genes leads...
To identify DNA sequences that target the somatic hypermutation process, the immunoglobulin gene promoter located upstream of the variable (V) region was duplicated upstream of the constant (C) region of a κ transgene. Normally, κ genes are somatically mutated only in the VJ region, but not in the C region. In B cell hybridomas from mice with this κ transgene (P5′C), both the VJ region and the C region,...
The exchange of HLA class II–associated invariant chain peptides (CLIP) for cognate peptide is catalyzed by HLA-DM under acidic conditions in vitro by an unknown mechanism. Here, we show an association between HLA-DM and HLA-DR in vivo by coprecipitation of the two heterodimers. The association is favored at low pH and in the nonionic detergent digitonin. Most DM–DR complexes are isolated from dense...
A model of lung eosinophilia based on the repeated exposure of mice to aerosolized OVA has been used to identify C–C chemokine genes expressed at stages of massive eosinophil infiltration. We describe the identification and cloning of a cDNA that encodes a mouse C–C chemokine with 68% amino acid identity to guinea pig Eotaxin. The recombinant protein encoded by this gene displays potent and specific...
Taking advantage of a potent MHC class I–restricted response that allows the identification of antigen- selected CD8 T cells directly ex vivo, we characterized the antigen-specific T cell repertoires that develop in individual mice by single-cell PCR analysis. Each of the immune mice displayed distinct yet structurally similar TCR repertoires. The overall repertoire size was estimated to be in the...
It is widely believed that viral clearance is mediated principally by the destruction of infected cells by CTLs. In this report, we use a transgenic mouse model of HBV replication to demonstrate that this assumption may not be true for all viruses. We find that adoptively transferred virus-specific CTLs can abolish HBV gene expression and replication in the liver without killing the hepatocytes. This...
Mice deficient in interleukin-5 (IL-5 −/− mice) were generated by gene targeting in embryonal stem cells. Contrary to previous studies, no obligatory role for IL-5 was demonstrated in the regulation of conventional B (B-2) cells, in normal T cell–dependent antibody responses or in cytotoxic T cell development. However, CD5 + B cells (B-1 cells) in the peritoneal cavity were reduced...
Cytolysis of target cells by natural killer (NK) cells and by some cytotoxic T cells occurs unless prevented by inhibitory receptors that recognize MHC class I on target cells. Human NK cells express a p58 inhibitory receptor specific for HLA-C. We report association of the tyrosine phosphatase HCP with the p58 receptor in NK cells. HCP association was dependent on tyrosine phosphorylation of p58...
Functional polymorphism in the rat peptide transporter associated with antigen processing (TAP) changes the peptide pool available for binding and presentation by a class I MHC allele, RT1.A a . The peptide binding motif for RT1.A a , determined by stabilization with synthetic peptides, included a strong preference for arginine at the peptide C terminus. Analysis of natural peptides...
Rearrangements of the IgH locus with J H joined to reading frame 2 of D H are greatly underrepresented in B cells. These rearrangements encode the truncated heavy chain Dμ. In pre-B cells, we found Dμ protein expressed on the cell surface and assembled into a complex with surrogate light chains, Igα, and Igβ. Cross-linking of either μm- or Dμm-containing pre-B cell receptors triggered...
IL-4 binds to a cell surface receptor complex that consists of the IL-4-binding protein (IL-4Rα) and the γ chain of the IL-2 receptor complex (γc). The receptors for IL-4 and IL-2 have several features in common; both use the γc as a receptor component, and both activate the Janus kinases JAK-1 and JAK-3. In spite of these similarities, IL-4 evokes specific responses, including the tyrosine phosphorylation...
To examine the hypothesis that a single initiating antigen was recognized by a monoclonal T cell population leading to subsequent inflammatory insulitis in nonobese (NOD) mouse islets, we examined the T cell receptor (TCR) Vβ repertoire of islet-infiltrating T cells in very young (2-week-old) NOD mice. In independent experiments, we repeatedly identified one monoclonal TCR β8.2 gene product expressed...
IL-4 causes hematopoietic cells to proliferate and express a series of genes, including CD23. We examined whether IL-4-mediated growth, as measured by 4PS phosphorylation, and gene induction were similarly controlled. Studies of M12.4.1 cells expressing human IL-4R truncation mutants indicated that the region between amino acids 557-657 is necessary for full gene expression, which correlated with...
Allelic exclusion at the IgH locus was examined in B lineage cells of wild-type mice and mice unable to express the surrogate light chain molecule λ5 using a single-cell PCR approach. By analyzing B precursor cells containing two V H D H J H rearrangements, we found that in wild-type animals, cells are allelically excluded as soon as μ chains are expressed. Furthermore, we...
The ability of chemokines, particularly MCP-1, to induce integrin-dependent binding of T lymphocytes to endothelial adhesion molecules or extracellular matrix (ECM) components was examined. MCP-1 induced significant adhesion to fibronectin (FN) and to endothelial-secreted ECM but not to purified ICAM-1 or VCAM-1, or to activated endothelium. The MCP-1-induced binding of T lymphocytes to FN was rapid,...
CIITA activates the expression of multiple genes involved in antigen presentation and it is believed to be required for both constitutive and IFNγ-inducible expression of these genes. To understand the role of CIITA in vivo, we have used gene targeting to generate mice that lack CIITA. CIITA-deficient (-/-) mice do not express conventional MHC class II molecules on the surface of splenic B cells and...
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