Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peritoneal exudate lymphocytes from immune guinea pigs that bind in vitro to autologous antigen-pulsed macrophages were allowed to proliferate for 1 week to give a population markedly enriched in antigen-specific T cells. This enriched population was then studied with regard to its binding to fresh autologous antigen-pulsed macrophages. Specific binding was not inhibited by a large excess of antigen in the media (5000-fold greater than the amount of antigen associated with the macrophages) either soluble or bound to Sepharose beads, or by coating the antigen-pulsed macrophags with antibody to the exogenous antigen, by reacting a second layer of antibody to the heterologous antibody, or by haptenating the antigen and treating the hapten-antigen macrophage complex with excess anti-hapten antibody. Results of treating antigen-pulsed macrophages with the proteolytic enzymes trypsin and pronase indicate that exogenous antigen is on the macrophage surface, but the experiments failed to prove that the removable antigen is essential for binding. The simplest interpretation of these results is that the T cell receptor is not specific for native exogenous antigen.
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PMID:Specific binding of T lymphocytes to macrophages. II. Role of macrophage-associated antigen. 30 85

Pretreatment of sheep erythrocytes with trypsin abolishes their specific binding and rosette formation with human T lymphocytes. A glycopeptide containing sialic acid is released from the intact sheep erythrocytes by incubation with trypsin and purified. This glycopeptide contains activity that can be bound to T lymphocytes and produces inhibition of rosette formation. This component with a m.w. of about 10,000 contains galactose, acetylglucosamine, acetylgalactosamine, sialic acid, and serine. These results suggest that the glycopeptide released by trypsin treatment may contain the site of the T cell receptor of sheep erythrocytes.
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PMID:Studies on glycopeptide released by trypsin from sheep erythrocytes. 93 29

GMP-140 (P-selectin), a 140-kDa granular membrane glycoprotein localized to the alpha granules of platelets and the Weibel-Palade bodies of endothelial cells, is thought to play an important role in adhesive interactions predominantly between granulocytes, platelets and vascular endothelial cells during inflammation. Although GMP-140 binds to granulocytes, its binding to lymphocytes has not been demonstrated. Using genetically engineered IgG C gamma 1 fusion protein of the extracellular domains of GMP-140, we demonstrate that GMP-140 binds to chronically antigen (Ag)-stimulated CD4+ T cells. Freshly isolated CD4+ T cells did not bind GMP-140, but priming and subsequent stimulation with alloantigen induced and gradually increased expression of GMP-140-reactive structures on their surface. T cells isolated from rheumatoid synovial fluids also exhibited strong binding to GMP-140. The binding of GMP-140 to primed T cells is not influenced by preactivation with phorbol 12-myristate 13-acetate, is almost completely abolished by pretreatment of T cells with neuraminidase or trypsin, and is also strongly inhibited by EDTA, the soluble sulfated glycans dextran sulfate, fucoidan, and heparin, but not by chondroitin sulfates. In spite of its strong binding to Ag-primed T cells, GMP-140 did not modulate the proliferative responses of these cells to various stimuli. However, GMP-140 in conjunction with anti-T cell receptor alpha beta monoclonal antibodies augmented the production of granulocyte-macrophage colony-stimulating factor GM-CSF and inhibited the production of interleukin-8 by Ag-primed T cells without influencing their tumor necrosis factor-alpha production. These results suggest that GMP-140 binds to chronically stimulated CD4+ T cells and differentially modulates their production of proinflammatory cytokines. The ability of Ag-primed T cells to bind GMP-140 may facilitate interactions with activated platelets and endothelial cells affecting the course of inflammation.
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PMID:GMP-140 (P-selectin/CD62) binds to chronically stimulated but not resting CD4+ T lymphocytes and regulates their production of proinflammatory cytokines. 137 17

Lymphokine-activated killer (LAK) cells exhibit major histocompatibility complex (MHC) unrestricted cytolysis against a wide variety of fresh and cultured tumor cells. Because previous work from our laboratory suggested that trypsin treatment of unseparated populations of LAK cells had a differential effect on lysis of different tumors, in this report we analyzed the lytic specificity of LAK cell clones against a panel of three different targets: MCA, B16 and YAC-1. We found that 21 out of the 24 analyzed murine spleen and bone marrow clones killed a combination of two, but not all three, of these tumor cells. Determinations of the phenotype of 10 LAK cell clones showed six with rearrangements for the T cell receptor (TCR) beta chain gene, suggesting a T cell origin, and four with germ line configurations for the TCR beta and delta chain genes, a result consistent with a non-T cell lineage. This cloning procedure provided an experimental tool to develop new procedures of adaptive immunotherapy.
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PMID:Differential lysis of tumor target cells displayed by lymphokine activated killer (LAK) cell clones. 161 70

This paper analyzes the conditions for in vitro tolerization of purified whole T cell populations and the consequences on helper and suppressor T cell functions. Highly purified splenic T cells from adult DBA/2 mice were incubated in vitro for 24 hr with high doses of trinitrophenyl coupled to human gamma-globulins (TNP-HGG). A profound inhibition of the TNP-specific helper function of these T lymphocytes was observed in a cooperative culture with normal purified splenic B cells and TNP-SRBC as antigen. This state of specific unresponsiveness was maintained after trypsin treatment of the cells, at the end of the 24-hr incubation with the tolerogen. We checked that this procedure removed the vast majority of F23.1 T cell receptor determinants from the cells. This result indicates that T cell receptors for antigen were not merely blocked by the tolerogen. In addition, B cells preincubated with tolerized T cells for 24 hr remained as responsive to TNP as B cells mixed with normal T cells in similar conditions. This demonstrates that the decreased response is not the result of secondary B cell tolerization. In addition, anti-Ia monoclonal antibodies were shown to block the induction of tolerance. We also showed that tolerized T cells significantly decreased the anti-TNP response of normal T and B cells in vitro, whereas the anti-SRBC response in the same cultures was unaffected. When tolerized T cells were separated into Lyt-2- and Lyt-2+ cells, it was found that tolerized Lyt-2- cells had lost about 75% of their helper activity and that Lyt-2+ cells suppressed 70% of the response of a normal T and B cell culture. Thus, in vitro induction of T cell tolerance results in a specific T cell unresponsiveness which is due to both helper T cell inactivation and induction of specific suppressor T cells.
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PMID:T cell tolerization in vitro: modulation of helper and suppressor cell activities. 243 86

Human retroviruses have recently been linked with T cell lymphoproliferative disorders and with the acquired immune deficiency syndrome. We investigated the mechanisms for acquired pure red cell aplasia and cutaneous anergy in a patient with the chronic T gamma-lymphoproliferative disease (T gamma-LPD) syndrome. Patient marrow erythroid progenitors (BFU-E) were 17 +/- 9% of control and were selectively increased to 88-102% of control after marrow T cell depletion. Patient Leu 2+ suppressor T cells spontaneously produced high titers of human gamma-interferon and resulted in a concentration-dependent selective inhibition (74-91%) of BFU-E when co-cultured with autologous or allogeneic marrow. Conditioned media (CM) derived from patient Leu 2+ T cells similarly inhibited growth of autologous or allogeneic marrow BFU-E. The inhibitory factor derived from patient CM was acid-labile (pH 2) and sensitive to trypsin; prior treatment of patient T cells with anti-HLA-DR monoclonal antibody plus complement abrogated the suppressive effect of T cell-derived CM. Patient peripheral blood mononuclear cells (PBMC) were unable to support growth of cultured interleukin 2 (IL 2)-dependent T cells, but responded to exogenous IL 2 in vitro with a 16-21-fold augmentation, relative to control, in mitogen-induced proliferation. Antibodies to HTLV-I core proteins p19 and p24 but not to HTLV-III proteins were detected in patient serum by Western blotting; patient cultured PBMC stained (7-11%) with antibodies to p19 and p24. Patient cultured PBMC demonstrated integrated HTLV-I genomic sequences by the Southern technique and expressed both specific HTLV-I genomic sequences by RNA dot blot plus reverse transcriptase activity. Utilizing a cloned DNA probe for the beta chain of the T cell receptor gene, patient PMBC demonstrated gene rearrangements providing presumptive evidence for clonality. The presence in serum of HTLV-I p19 and p24 antibodies, the expression of p19 and p24 core antigens on patient mononuclear cells, the evidence of HTLV-I proviral integration sequences and the expression of HTLV-I genomic sequences in patient cells, indicates infection with HTLV-I and raises the possibility of an etiologic link between human retrovirus infection and some instances of large granular lymphocytic leukemia (T gamma-LPD).
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PMID:Human T cell leukemia virus-I-associated T-suppressor cell inhibition of erythropoiesis in a patient with pure red cell aplasia and chronic T gamma-lymphoproliferative disease. 289 60

The YE1/48 antigen, defined by two rat monoclonal antibodies YE1/48 and YE1/32, is a disulfide-linked dimer of 45- to 50-kDa subunits expressed on murine T cells. It has previously been described as a T cell receptor alpha/beta-like molecule because of its similar m.w., dimeric structure, and isoelectric points comparable to those of the murine T cell receptor. We have now further characterized this antigen, directly compared it with the T cell receptor, and obtained internal amino acid sequences from the purified and trypsin-digested antigen. Endoglycosidase F treatment revealed the peptide cores of the antigen to be approximately 32 to 38kDa under reducing conditions and they possess at least three glycosylation side-chains. On diagonal gel analysis (nonreducing vs reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis), the YE1/48 antigen and the T cell antigen receptor alpha/beta immunoprecipitated from thymocytes are indistinguishable. However, the two molecules can be distinguished on EL-4 cells by sequential immunoprecipitation using the YE1/48 monoclonal antibody and a rabbit antiserum reactive with the murine T cell receptor. Furthermore, two MBL-2 variant clones, which differ in the level of YE1/48 antigen expression by more than 200-fold, express comparable level of the T cell receptor. Therefore, the YE1/48 antigen and the T cell antigen receptor alpha/beta seem to be different molecules. The YE1/48 antigen was purified from MBL-2(4.1) cells by affinity chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis, digested with trypsin and the resultant peptides were separated by reverse phase high performance liquid chromatography. The amino acid sequences of several of the YE1/48 tryptic peptides were determined. Upon comparison with the protein sequences in the data base, no identical sequences were detected. These results demonstrated that the YE1/48 antigen is clearly different from the T cell receptor alpha-, beta-, or gamma- chain gene products, and it is a novel T cell antigen not previously described. However, the possibility of homology with other proteins remains undetermined because the tryptic peptides are too short to yield meaningful statistical comparison with the data base.
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PMID:Characterization of a murine T cell surface disulfide-linked dimer of 45-kDa glycopeptides (YE1/48 antigen). Comparison with T cell receptor, purification, and partial amino acid sequences. 312 37

Macrophages play a requisite role in the induction and expression of T lymphocyte responses to Listeria monocytogenes. For effective T cell-macrophage interaction to occur, macrophages must perform at least two fundamental functions. They must take up and handle the antigen, and they must express appropriate membrane glycoproteins encoded for by the I-region of murine major histocompatibility gene complex (Ia molecules). Data collected in a murine model suggests that the following sequential events are involved in the Listeria-macrophage-T cell interaction. Listeria interaction with macrophage cell surface via trypsin sensitive structures. Interiorization within phagosomes. Phagosome-lysosome fusion. Partial degradation of Listeria. Transfer of protein antigen fragments to macrophage cell surface. Recognition of macrophage surface antigen and I-region associated (Ia) molecules by the T cell receptor. The essential feature of this model is that: antigen handling occurs intracellularly and independently of macrophage cell surface Ia molecules. With regard to the survival advantage of this mechanism, one may speculate that the degradation of pathogens by macrophages may serve to increase the number of different structural moieties which can act as antigens. Thus, bacterial components normally sequestered in the interior of organisms could conceivably serve as antigens, and the multiplicity of such antigenic determinants would make it less likely that a nonresponder status with respect to I-region gene function would be generated. This mechanism may be especially relevant to host defense against intracellular pathogens such as Listeria monocytogenes.
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PMID:The processing and presentation of Listeria monocytogenes antigens by macrophages. 644 50

The peptides recognized by an H-2Db-restricted CD8 cytotoxic T lymphocyte (CTL) clone which is specific for the 60-kDa mycobacterial heat shock protein (hsp) and cross-reacts with stressed host cells were characterized. None of the nonapeptides from hsp60 conforming to the H-2Db binding motif were able to sensitize target cells for lysis by this CTL clone. Sequence analysis of the stimulatory fraction from a trypsin digest of hsp60, together with synthetic peptide studies, defined a cluster of overlapping epitopes. Carboxy-terminal extension by at least one amino acid of the nonamer predicted to bind best to H-2Db was essential for CTL recognition. Two such elongated peptides, a 10-mer and a 12-mer stimulated the clone at similarly low concentrations in the 100 pM range. We assume that these two peptides comply best with the natural epitope. In contrast, the 11-mer was inactive. The stimulatory 10-mer bound to H-2Db with an efficacy similar to that of the nonapeptide corresponding to the H-2Db motif, as revealed by peptide induced major histocompatibility complex (MHC) surface expression on RMA-S cells and competitive blocking of epitope recognition by the nonamer. Binding of these carboxy-terminally extended peptides to the MHC groove can be explained by anchoring through the amino acid residue Asn in position 5 of the peptide and by intrusion of the hydrophobic carboxy-terminal Ala (10-mer) or Leu (12-mer), but not Gly (11-mer), into the hydrophobic pocket of the H-2Db cleft. Because the carboxy-terminal part is thus larger than predicted, this region of the peptide may arch up from the binding groove. We assume that recognition of steric components of the MHC/peptide complex broaden the range of epitope specificity for a single T cell receptor. This flexibility not only promotes recognition of several overlapping peptides from a single antigen, but may also increase the chance of cross-reaction with similar peptides from unrelated proteins, including autoantigens. Consistent with this latter assumption, the T cell clone cross-recognizes mycobacterial hsp60 and stressed host cells.
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PMID:Elongated peptides, not the predicted nonapeptide stimulate a major histocompatibility complex class I-restricted cytotoxic T lymphocyte clone with specificity for a bacterial heat shock protein. 780 44

The influenza virus hemagglutinin is synthesized as a single polypeptide chain, but upon maturation it will posttranslationally be modified by a host cell related trypsin-like enzyme. The enzymatic cleavage attacks the so-called intersubunit region of the molecule giving rise to covalently linked HA1 and HA2 subunits. An I-Ed-restricted T cell epitope was identified in the highly conserved intact intersubunit region of the influenza virus hemagglutinin. T cell recognition of a 25-mer synthetic peptide comprising the intact intersubunit region does not require further processing and the elimination of the intervening Arg residue coupling the fusion peptide to the C-terminal segment of HA1 does not abolish the T cell activating capacity. The fine specificity pattern of a T cell hybridoma similar to that of the polyclonal T cell response demonstrates that a single T cell receptor is able to recognize peptides of different sizes representing not only the uncleaved but also the cleaved form of this hemagglutinin region. Based on specificity studies the epitope was localized to the C-terminal 11 amino acids of the HA1 subunit. The cross-reactivity of peptide-primed T cells with influenza virus infected antigen-presenting cells shows that fragments comprising the identified epitope of the intersubunit region can be generated as a result of natural processing of the hemagglutinin molecule. As antigen-presenting cells are lacking the enzyme which is responsible for the posttranslational modification of newly synthesized hemagglutinin molecules, the role of immature viral proteins in immune recognition is discussed.
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PMID:T cell recognition of the posttranslationally cleaved intersubunit region of influenza virus hemagglutinin. 782 66


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