Jack Strominger
Harvard University, Stem Cell and Regenerative Biology, Faculty Member
Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy. β... more
Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy. β 2-microglobulin(β 2m) labeled with a single fluorophore, was exchanged at the surface of B cell transfectants to specifically mark cell surface and endocytosed class I MHC protein. Intracellular β
Research Interests: Fluorescent Dyes and Reagents, Confocal Microscopy, Multidisciplinary, Cell line, Humans, and 11 moreEndocytosis, Enterotoxins, Endoplasmic Reticulum, Transferrin Receptor, Green Fluorescent Protein, Lipid Raft, B Lymphocytes, Golgi Apparatus, Plasma Membrane, Endosomes, and Low Density Lipoprotein (LDL)
A new retrovirus vector containing the gene for hygromycin B resistance (hyg) as a selectable marker under the control of an internal simian virus 40 promoter was constructed. It was used, together with an analogous previously described... more
A new retrovirus vector containing the gene for hygromycin B resistance (hyg) as a selectable marker under the control of an internal simian virus 40 promoter was constructed. It was used, together with an analogous previously described vector, DO1, which contains the gene for G418 resistance, to introduce and express the genes for the two chains of a human class II major histocompatibility complex antigen in NIH 3T3 cells. In addition, these vectors were used to express DR antigens in two human mutant B-lymphoblastoid cell lines, one of which was deleted for both alleles of the DR alpha gene and the other of which expressed no class II antigens because of a genetic defect in a putative trans-acting regulatory factor.
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The tumor necrosis factor (TNF) alpha and beta gene pair has been linked in the human major histocompatibility complex to HLA-B, HLA-C, and, tentatively, HLA-E and HLA-A on one side and to the class III complement/steroid 21-hydroxylase... more
The tumor necrosis factor (TNF) alpha and beta gene pair has been linked in the human major histocompatibility complex to HLA-B, HLA-C, and, tentatively, HLA-E and HLA-A on one side and to the class III complement/steroid 21-hydroxylase gene cluster on the other by pulsed-field gel electrophoresis. The TNF genes are located 200 kilobases (kb) centromeric of HLA-B and about 350 kb telomeric of the class III cluster. Together with previous data on the linkage and structures of the class II and class III regions, a restriction map of the entire human major histocompatibility complex of about 3500 kb has been prepared.
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In addition to their role in peptide antigen presentation, class I MHC proteins also play a critical role in inhibiting natural killer (NK) cytotoxicity through interaction with NK inhibitory receptors. Thus, NK cells are cytotoxic to... more
In addition to their role in peptide antigen presentation, class I MHC proteins also play a critical role in inhibiting natural killer (NK) cytotoxicity through interaction with NK inhibitory receptors. Thus, NK cells are cytotoxic to virus-infected and tumor cells that have lost class I MHC protein expression. However, the nature of the receptors involved in the triggering of lysis
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Immune interferon (IFN-gamma ) increases the surface expression of HLA-A,B antigens and induces the surface expression of HLA-DR antigens on vascular endothelial cells and dermal fibroblasts. Here we report that IFN-gamma induces parallel... more
Immune interferon (IFN-gamma ) increases the surface expression of HLA-A,B antigens and induces the surface expression of HLA-DR antigens on vascular endothelial cells and dermal fibroblasts. Here we report that IFN-gamma induces parallel expression of two other class II major histocompatibility complex (MHC) antigens, SB and DC. Maximal surface expression of all three antigens is reached in 4--6 days, and
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Abstract The peptide binding cleft of the class I human histocompatibility antigen, HLA-A2, contains conserved amino acid residues clustered in the two ends of the cleft in pockets A and F as well as polymorphic residues. The function of... more
Abstract The peptide binding cleft of the class I human histocompatibility antigen, HLA-A2, contains conserved amino acid residues clustered in the two ends of the cleft in pockets A and F as well as polymorphic residues. The function of two conserved tyrosines in the A ...
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The cytotoxicity of human natural killer (NK) cells is modulated by the major histocompatibility complex human leukocyte antigen (HLA)-C molecules on the surface of the target cell. Alloreactive NK cells specific for the NK-1 alloantigen... more
The cytotoxicity of human natural killer (NK) cells is modulated by the major histocompatibility complex human leukocyte antigen (HLA)-C molecules on the surface of the target cell. Alloreactive NK cells specific for the NK-1 alloantigen could be reproducibly generated from individuals that were homozygous for HLA-C with asparagine at residue 77 and lysine at residue 80 [HLA-C(Asn77,Lys80)] by stimulation with target cells that were homozygous for HLA-C(Ser77,Asn80); the reciprocal stimulation yielded NK cells specific for the NK-2 alloantigen. However, neither homozygous target cell stimulated the generation of alloreactive NK cells from heterozygous individuals. Thus, these data reveal an unanticipated difference between human NK alloreactivity defined by this system and murine "hybrid resistance."
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The outermost layer of the human placenta is devoid of classical class I human leukocyte antigens (HLA-A, HLA-B, and HLA-C) and class II proteins (HLA-DR, HLA-DQ, and HLA-DP). Although this prevents recognition by maternal T lymphocytes,... more
The outermost layer of the human placenta is devoid of classical class I human leukocyte antigens (HLA-A, HLA-B, and HLA-C) and class II proteins (HLA-DR, HLA-DQ, and HLA-DP). Although this prevents recognition by maternal T lymphocytes, the lack of class I molecules leaves these cells susceptible to attack by natural killer (NK) cells. However, trophoblast cells directly in contact with the maternal tissues express the class I molecule HLA-G, which may be involved in protecting the trophoblast from recognition by NK cells. Here evidence is provided that expression of HLA-G is sufficient to protect otherwise susceptible target cells from lysis by activated NK1 and NK2 cell lines and clones that are specific for distinct groups of HLA-C alleles. The receptors on NK cells that recognize HLA-G are also identified.
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The T-cell receptor for antigen (Ti) was purified from the human tumor cell line HPB-ALL. Amino-terminal sequence analysis of an acid-cleaved peptide of the Ti alpha chain showed that it is highly homologous to a putative murine alpha... more
The T-cell receptor for antigen (Ti) was purified from the human tumor cell line HPB-ALL. Amino-terminal sequence analysis of an acid-cleaved peptide of the Ti alpha chain showed that it is highly homologous to a putative murine alpha chain recently described. Amino-terminal sequence analysis of the Ti beta chain revealed that it shares 50 percent homology with the Ti beta chain amino acid sequences from two other human T-cell tumors. Nucleotide sequence analysis of a complementary DNA clone encoding the Ti beta chain from the HPB-MLT cell line showed that this chain represents a second human constant region gene segment and suggested that it arises from direct joining of the variable and joining gene segments without any intervening D region sequences.
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Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy.... more
Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy. beta(2)-microglobulin (beta(2)m), labeled with a single fluorophore, was exchanged at the surface of B cell transfectants to specifically mark cell surface and endocytosed class I MHC protein. Intracellular beta(2)m colocalized with fluorophore-conjugated transferrin, implying that class I MHC protein endocytosed into early endosomes. These endosomes containing fluorescent beta(2)m were found close to or within the Golgi apparatus, marked by fluorescent ceramide. Even after 24 hr of incubation, very little fluorescent beta(2)m was found in intracellular organelles stained by DiOC(6), marking the endoplasmic reticulum, or fluorophore-conjugated low density lipoprotein, marking late endosomes and lysosomes. Fluorophore-conjugated superantigens (staphylococcal enterotoxin A and B), presumed to enter cells bound to class II MHC protein, also were found to endocytose into beta(2)m-containing early endosomes. Staining with mAb and use of transfectants expressing MHC protein attached to green fluorescent protein confirmed the presence of intracellular compartments rich in both class I and II MHC protein and demonstrated that class I and II MHC protein also colocalize in discrete microdomains at the cell surface. These cell surface microdomains also contained transferrin receptor and often were juxtaposed to cholesterol-rich lipid rafts. Thus, class I and II MHC protein meet in microdomains of the plasma membrane and endocytose into early endosomes, where both may acquire and present exogenous antigen.
Research Interests: Fluorescent Dyes and Reagents, Confocal Microscopy, Multidisciplinary, Cell line, Humans, and 11 moreEndocytosis, Enterotoxins, Endoplasmic Reticulum, Transferrin Receptor, Green Fluorescent Protein, Lipid Raft, B Lymphocytes, Golgi Apparatus, Plasma Membrane, Endosomes, and Low Density Lipoprotein (LDL)
Three preparations of purified papain-solublized HL-A antigens have been radiolabeled by reductive methylation using formaldehyde and potassium boro[3H]hydride, and their reaction with specific HL-A antisera has been investigated. Greater... more
Three preparations of purified papain-solublized HL-A antigens have been radiolabeled by reductive methylation using formaldehyde and potassium boro[3H]hydride, and their reaction with specific HL-A antisera has been investigated. Greater than 99 percent of the radioactivity in the [3H]HL-A2 preparation could be complexed with several HL-A2 antisera, but not with specificity controls. The other two preparations, which contained mixtures of HL-A antigenic specificities (HL-A7,12 an HL-A3,W25;12,27), showed 63 per cent and 70 per cent complex formation with mixtures of the appropriate HL-A antisera. The N-terminal amino acid of both subunits has been determined for the three HL-A antigen preparations. In all cases the only detectable N-terminal amino acids were isoleucine for the small subunits, beta-2-microblogulin, and glycine for the larger subunit.
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Recombinant human tumor necrosis factor (TNF), purified to greater than 99% homogeneity, increases surface expression of class I major histocompatibility complex (MHC) antigens to a maximum of 9-fold on cultured human endothelial cells... more
Recombinant human tumor necrosis factor (TNF), purified to greater than 99% homogeneity, increases surface expression of class I major histocompatibility complex (MHC) antigens to a maximum of 9-fold on cultured human endothelial cells (HEC) and human dermal fibroblasts (HDF). The increase is concentration dependent (peak 20-100 units/ml) and time dependent (nearly maximal by 4 days); expression remains elevated in the continued presence of TNF and requires greater than 7 days to return to basal levels upon TNF withdrawal. The increase in surface expression appears to result from increases in steady-state mRNA levels for the class I antigens, although the increase in mRNA is proportionately greater than for surface expression. No surface expression of or mRNA for class II MHC antigens is detectable in either control or TNF-treated HEC or HDF. These effects are similar to those produced by leukocyte or fibroblast (type I) interferons (IFNs). The protein synthesis inhibitor cycloheximide (CHX), when added coincidentally with type I IFNs, leads to superinduction of mRNA for class I MHC antigens and, unexpectedly, leads to the appearance of mRNA for class II MHC antigens. CHX has no effect by itself upon mRNA levels for class I or class II MHC antigens, nor does it modulate the increases in mRNA produced by immune (type II) IFN. Most interesting, CHX blocks the increase in mRNA for class I MHC antigens induced by TNF. Thus TNF appears to act on MHC gene expression through a newly synthesized protein intermediate. Our results provide direct evidence that TNF can modulate gene expression in normal (untransformed) cell types and contribute to understanding the complex nature of MHC gene regulation. Finally, they suggest that TNF may act in vivo as an immunoregulatory molecule.
Research Interests: Gene regulation, Gene expression, Multidisciplinary, Protein synthesis, Humans, and 12 moreSkin, Glycoproteins, Steady state, Time Dependent, Endothelial cell, Major histocompatibility complex, Tumor necrosis factor-alpha, ENDOTHELIUM, Human Fibroblasts, Recombinant Proteins, Tumor Necrosis Factor–α (TNF), and Gene Expression Regulation
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Purified, papain-solubilized preparations of HL-A antigen from cultured human lymphoblastoid cells (HL-A2 and HL-A7,12 from RPMI 4265 cells and a mixture of HL-A3, W-25, HL-A12, and HL-A27 from IM-1 cells) show substantial charge... more
Purified, papain-solubilized preparations of HL-A antigen from cultured human lymphoblastoid cells (HL-A2 and HL-A7,12 from RPMI 4265 cells and a mixture of HL-A3, W-25, HL-A12, and HL-A27 from IM-1 cells) show substantial charge heterogeneity in isoelectric focusing gels. This heterogeneity can be ascribed largely to variable numbers of sialic acid residues on each molecule. Neuraminidase (EC 3.2.1.18) treatment of the HL-A antigens as a function of time altered the band patterns in a manner demonstrating that up to three sialic acid residues are present on both first locus ("LA") and second locus ("Four") antigens. Neuraminidase treatment did not alter the specificity or specific activity of the purified antigens.
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Framework monoclonal antibodies have identified a population of human lymphocytes that express the T3 glycoprotein but not the T-cell receptor (TCR) alpha- and beta-subunits. Chemical crosslinking experiments reveal that these lymphocytes... more
Framework monoclonal antibodies have identified a population of human lymphocytes that express the T3 glycoprotein but not the T-cell receptor (TCR) alpha- and beta-subunits. Chemical crosslinking experiments reveal that these lymphocytes express novel T3-associated polypeptides, one of which appears to be the product of the T gamma gene. The other polypeptide may represent a fourth TCR subunit, designated T delta.
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The T1/Leu-1/CD5 molecule, a human T-cell surface glycoprotein of relative molecular mass (Mr) 67,000, has been implicated in the proliferative response of activated T cells and in T-cell helper function. A similar involvement in T-cell... more
The T1/Leu-1/CD5 molecule, a human T-cell surface glycoprotein of relative molecular mass (Mr) 67,000, has been implicated in the proliferative response of activated T cells and in T-cell helper function. A similar involvement in T-cell proliferation has been reported for Ly-1, the murine homologue of T1. Here we report the complete amino-acid sequence of the T1 precursor molecule deduced from complementary DNA clones. The protein contains a classical signal peptide; a 347-amino-acid extracellular segment; a transmembrane region; and a 93-amino-acid intracellular segment. The extracellular segment contains many cysteine residues and is composed of two related structural domains separated by a proline/threonine-rich region. The T1 molecule has structural features characteristic of other receptor molecules.
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Research Interests: Transcription Factors, T cell receptor, Protein synthesis, Humans, Methylation, and 12 moreThe, Cyclosporine, T lymphocytes, Protein Complex Detection, Model System, Tumor necrosis factor-alpha, Experimental Medicine, Base Sequence, Tumor Necrosis Factor–α (TNF), DNA binding proteins, Protein Biosynthesis, and Gene Expression Regulation
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The expression, or lack thereof, of class I MHC glycoproteins has a marked influence on natural killer cell function. Cells which do not express class I MHC molecules are susceptible to lysis by NK cells, and transfection of these targets... more
The expression, or lack thereof, of class I MHC glycoproteins has a marked influence on natural killer cell function. Cells which do not express class I MHC molecules are susceptible to lysis by NK cells, and transfection of these targets with class I MHC genes can render these cells resistant to NK attack. This inhibition of NK-killing is mediated by a novel family of receptors expressed mainly on NK cells, but also found on some T-cells. The function of these class I MHC binding receptors when expressed on T-cells is discussed also and a novel co-stimulatory activity of NKAR described. Lastly, a novel mechanism by which human cytomegalovirus evades immune surveillance by NK cells is documented.
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The protection of cells expressing class I HLA molecules from NK lysis is mediated by natural killer cell inhibitory receptors (NKIR). Using site-directed mutagenesis, residues on HLA-C that determine the locus specificity (alphaVal-76),... more
The protection of cells expressing class I HLA molecules from NK lysis is mediated by natural killer cell inhibitory receptors (NKIR). Using site-directed mutagenesis, residues on HLA-C that determine the locus specificity (alphaVal-76), allotype group specificity (a dimorphism alphaAsn-80/Lys-80), and affinity of NKIR binding (a second pair of dimorphisms, alphaAla-73, Asp-90 or alphaThr-73, Ala-90) have been identified. Thus the "footprint" of the NKIR on the alpha1 helix of the class I MHC molecule HLA-C and its associated beta strands are similar in position to the site occupied by superantigens on and behind the alpha1 helix of the class II MHC molecule HLA-DR1, but further toward its C-terminus. The intermediate affinity binding of NKIR to HLA-C, determined by alpha73 and alpha90, has an essential role in preventing cross-reactivity and ensuring the availability of NK cells for immunosurveillance; low affinity and high affinity mutants are both physiologically impaired.
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A Nomenclature Committee composed of geneticists and immunologists, including specialists in tissue typing, has met after each of the Histocompatibility Workshops beginning with the Third Workshop in 1967. The Committee, in part under the... more
A Nomenclature Committee composed of geneticists and immunologists, including specialists in tissue typing, has met after each of the Histocompatibility Workshops beginning with the Third Workshop in 1967. The Committee, in part under the auspices of the World Health Organization and the International Union of Immunological Societies (WHO/IUIS), met after the Sixth Workshop in Aarhus in July 1975. The expanding knowledge of the genetics of the major histocompatibility system of man has necessitated a revision of the terminology for the HLA region following the principles established in previous reports. This has been done with as few changes as possible.
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Influenza matrix peptide 58-66 is shown to be the optimal nonamer for binding to HLA-A2 and presentation to cytotoxic T lymphocytes (CTL). If titered out to 2 x 10(-10) - 4 x 10(-10) M in CTL-mediated lysis assays and to 3 x 10(-9) M in... more
Influenza matrix peptide 58-66 is shown to be the optimal nonamer for binding to HLA-A2 and presentation to cytotoxic T lymphocytes (CTL). If titered out to 2 x 10(-10) - 4 x 10(-10) M in CTL-mediated lysis assays and to 3 x 10(-9) M in an HLA-A2 assembly-stabilization assay in cell lysates. The peptide was shown to make probable contacts with its carboxy terminus close to residue 116 in the floor of the cleft of HLA-A2, close to the F pocket. The side chain of the amino-terminal amino acid was unimportant, but its free amino and carbonyl groups in the A pocket appeared important in optimizing peptide presentation. The B pocket probably accommodates the side chain of residue 2 (isoleucine) and was shown to be critical in peptide presentation.
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Invading human leukocyte antigen-G+ (HLA-G+) extravillous trophoblasts (EVT) are rare cells that are believed to play a key role in the prevention of a maternal immune attack on foreign fetal tissues. Here highly purified HLA-G+ EVT and... more
Invading human leukocyte antigen-G+ (HLA-G+) extravillous trophoblasts (EVT) are rare cells that are believed to play a key role in the prevention of a maternal immune attack on foreign fetal tissues. Here highly purified HLA-G+ EVT and HLA-G- villous trophoblasts (VT) were isolated. Culture on fibronectin that EVT encounter on invading the uterus increased HLA-G, EGF-Receptor-2, and LIF-Receptor expression on EVT, presumably representing a further differentiation state. Microarray and functional gene set enrichment analysis revealed a striking immune-activating potential for EVT that was absent in VT. Cocultures of HLA-G+ EVT with sample matched decidual natural killer cells (dNK), macrophages, and CD4+ and CD8+ T cells were established. Interaction of EVT with CD4+ T cells resulted in increased numbers of CD4+CD25(HI)FOXP3+CD45RA+ resting regulatory T cells (Treg) and increased the expression level of the Treg-specific transcription factor FOXP3 in these cells. However, EVT did not enhance cytokine secretion in dNK, whereas stimulation of dNK with mitogens or classical natural killer targets confirmed the distinct cytokine secretion profiles of dNK and peripheral blood NK cells (pNK). EVT are specialized cells involved in maternal-fetal tolerance, the properties of which are not imitated by HLA-G-expressing surrogate cell lines.
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MLL5 is a mammalian trithorax group (trx-G) gene identified within chromosome band 7q22, a frequently deleted element found in cytogenetic aberrations of acute myeloid malignancies. MLL5 cDNA was linked with the FLAG and V5 tags at the N... more
MLL5 is a mammalian trithorax group (trx-G) gene identified within chromosome band 7q22, a frequently deleted element found in cytogenetic aberrations of acute myeloid malignancies. MLL5 cDNA was linked with the FLAG and V5 tags at the N and C terminus, respectively, and transfected into 293T cells. Immunofluoresence staining of the expressed tagged MLL5 protein showed localization to the nucleus and exclusion from nucleoli, and no surface staining was detected. Both ectopically introduced and endogenous MLL5 protein displayed a speckled nuclear distribution. By using a series of MLL5-truncated mutants fused with enhanced GFP, a domain (residues 945-1,156) required for foci accumulation was identified, and regions containing functional nuclear localization signals were mapped. Ectopic overexpression of GFP-MLL5 induced cell cycle arrest in G(1) phase. This inhibition of cell cycle progression was indicated by delayed progression into nocodazole-induced mitotic arrest and was confirm...
Research Interests: Cell Cycle, Confocal Microscopy, Gene expression, Multidisciplinary, Cell Division, and 12 moreCell line, Acute Myeloid Leukemia, Humans, Animals, Chromatin remodeling, Chromatin, Protein Complex Detection, Cell nucleus, HeLa cells, Cell Cycle Arrest, DNA binding proteins, and Nuclear localization signal
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Type 1 diabetes (insulin-dependent diabetes mellitus, IDDM) is a disease controlled by the major histocompatibility complex (MHC) which results from T-cell-mediated destruction of pancreatic beta-cells. The incomplete concordance in... more
Type 1 diabetes (insulin-dependent diabetes mellitus, IDDM) is a disease controlled by the major histocompatibility complex (MHC) which results from T-cell-mediated destruction of pancreatic beta-cells. The incomplete concordance in identical twins and the presence of autoreactive T cells and autoantibodies in individuals who do not develop diabetes suggest that other abnormalities must occur in the immune system for disease to
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ABSTRACT
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Quantitative and qualitative defects in CD1-restricted natural killer T cells have been reported in several autoimmune-prone strains of mice, including the nonobese diabetic (NOD) mouse. These defects are believed to be associated with... more
Quantitative and qualitative defects in CD1-restricted natural killer T cells have been reported in several autoimmune-prone strains of mice, including the nonobese diabetic (NOD) mouse. These defects are believed to be associated with the emergence of spontaneous autoimmunity. Here we demonstrate that both CD1d-null NOD and CD1d-null NOD/BDC2.5 T cell receptor transgenic mice have an accelerated onset and increased incidence
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ItL-A antigens prepared from human lymphoid cells by treatment of either intact cells or membranes with papain or nonionic detergents have been shown to contain two polypeptide chains. The antigen prepared by treatment of cells or cell... more
ItL-A antigens prepared from human lymphoid cells by treatment of either intact cells or membranes with papain or nonionic detergents have been shown to contain two polypeptide chains. The antigen prepared by treatment of cells or cell membranes with papain contains polypeptide chains with a mol wt of about 34,000 and 11,000 (1), whereas the detergent-solubilized antigen has polypeptides of
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Human natural killer (NK) cells with the CD3^- CD16^+ phenotype recognize allospecificities on normal T-cell blasts. The NK-defined specificity 1 (NK-1) is recessively inherited and has been mapped to the major histocompatibility complex... more
Human natural killer (NK) cells with the CD3^- CD16^+ phenotype recognize allospecificities on normal T-cell blasts. The NK-defined specificity 1 (NK-1) is recessively inherited and has been mapped to the major histocompatibility complex between the complement gene cluster and HLA-A. A gene for NK-1, however, has not been identified. Here we demonstrate that NK-1 and the recently defined NK specificity
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HLA-G is the putative natural killer (NK) cell inhibitory ligand expressed on the extravillous cytotrophoblast of the human placenta. Killing of the class I negative human B cell line 721.221 by NK cells is inhibited by the expression of... more
HLA-G is the putative natural killer (NK) cell inhibitory ligand expressed on the extravillous cytotrophoblast of the human placenta. Killing of the class I negative human B cell line 721.221 by NK cells is inhibited by the expression of HLA-G. This inhibition is dependent on a high level of HLA-G expression. In the present study, the nature of the receptors
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Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy.... more
Class I MHC protein primarily presents endogenous antigen but also may present exogenous antigen. Here, we investigated the intracellular pathway of spontaneously internalized class I MHC protein by confocal microscopy. beta(2)-microglobulin (beta(2)m), labeled with a single fluorophore, was exchanged at the surface of B cell transfectants to specifically mark cell surface and endocytosed class I MHC protein. Intracellular beta(2)m colocalized with fluorophore-conjugated transferrin, implying that class I MHC protein endocytosed into early endosomes. These endosomes containing fluorescent beta(2)m were found close to or within the Golgi apparatus, marked by fluorescent ceramide. Even after 24 hr of incubation, very little fluorescent beta(2)m was found in intracellular organelles stained by DiOC(6), marking the endoplasmic reticulum, or fluorophore-conjugated low density lipoprotein, marking late endosomes and lysosomes. Fluorophore-conjugated superantigens (staphylococcal enterotoxin A and B), presumed to enter cells bound to class II MHC protein, also were found to endocytose into beta(2)m-containing early endosomes. Staining with mAb and use of transfectants expressing MHC protein attached to green fluorescent protein confirmed the presence of intracellular compartments rich in both class I and II MHC protein and demonstrated that class I and II MHC protein also colocalize in discrete microdomains at the cell surface. These cell surface microdomains also contained transferrin receptor and often were juxtaposed to cholesterol-rich lipid rafts. Thus, class I and II MHC protein meet in microdomains of the plasma membrane and endocytose into early endosomes, where both may acquire and present exogenous antigen.
Research Interests: Fluorescent Dyes and Reagents, Confocal Microscopy, Multidisciplinary, Cell line, Humans, and 11 moreEndocytosis, Enterotoxins, Endoplasmic Reticulum, Transferrin Receptor, Green Fluorescent Protein, Lipid Raft, B Lymphocytes, Golgi Apparatus, Plasma Membrane, Endosomes, and Low Density Lipoprotein (LDL)
CD1d-restricted T cells contribute to tumor protection, but their precise roles remain unclear. Here we show that tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor induce the expansion of CD1d-restricted T... more
CD1d-restricted T cells contribute to tumor protection, but their precise roles remain unclear. Here we show that tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor induce the expansion of CD1d-restricted T cells through a mechanism that involves CD1d and macrophage inflammatory protein 2 expression by CD8-, CD11c+ dendritic cells (DCs). The antitumor immunity stimulated by vaccination with irradiated, granulocyte-macrophage colony-stimulating