Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During antigen presentation, a close association between CD4 and the T cell receptor (TCR) occurs as a result of interacting with the same major histocompatibility complex class II molecule. The potential consequences of such an intimate interaction on TCR specificity was addressed using CD4 loss variants of four different murine T cell hybridomas specific for the immunodominant hen egg lysozyme (HEL) peptide 46-61. While all the CD4+ and CD4- variants tested possessed comparable surface expression of TCR, CD3, CD2 and LFA-1, and responded similarly to immobilized anti-TCR and anti-CD3 monoclonal antibodies, they differed dramatically in their responses to either the naturally processed HEL antigen, synthetic peptide 46-61 or staphylococcal enterotoxin superantigens. While one hybridoma was comparatively unaffected by the loss of CD4, another lost its responsiveness to antigen and peptide completely while retaining reactivity to SE. In contrast, two other hybridomas still responded to antigen but lost reactivity to synthetic peptide and SE. These data could not be readily explained on the basis of affinity or signal transduction requirements alone, and thus suggest that the intimate association of CD4 with the TCR may result in a subtle modulation of its fine specificity for some but not all T cells.
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PMID:Does CD4 help to maintain the fidelity of T cell receptor specificity? 162 97

In the absence of serum, nonpiliated gonococci expressing PII outer membrane proteins (PIIs) adhere to human neutrophils whereas non-PII-expressing (PII-) gonococci do not. After an observation that neutrophils in monolayers bound more gonococci than neutrophils in suspension, we treated neutrophil suspensions with known stimulants of degranulation and measured subsequent gonococcal adherence to suspended neutrophils. The chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fmlp), the potent secretagogue phorbol myristate acetate, and the calcium ionophore A23187 all caused increased adherence of PII+ gonococci, but not PII- gonococci, to neutrophils in a dose-responsive manner. Increased adherence of gonococci to neutrophils was paralleled by increased degranulation of neutrophil myeloperoxidase, lysozyme, and lactoferrin. Inhibition of fmlp-induced neutrophil degranulation by pertussis toxin, the calmodulin inhibitors trifluoperazine and N-5-chloronaphthalene sulfonamide, or the intracellular calcium-binding agent trimethoxybenzoic acid also inhibited fmlp-induced gonococcal adherence to neutrophils. Neither undifferentiated nor myelocytically differentiated HL-60 cells, which possess primary but defective or nonexistent secondary granules, bound PII+ or PII- gonococci. Gonococci did not adhere to human monocytes, monocyte-derived macrophages, lymphocytes, platelets, or erythrocytes, indicating that several receptors, such as the complement receptors CR1, CR3 (CD11b/CD18), and CR4 (CD11c/CD18) or the adherence complex LFA-1 (CD11a/CD18), were probably not involved in gonococcal adherence to human neutrophils.
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PMID:Up-regulation of human neutrophil receptors for Neisseria gonorrhoeae expressing PII outer membrane proteins. 211 69

The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6-fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12-binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation.
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PMID:Expression of specific granule markers on the cell surface of neutrophil cytoplasts. 351 66

T cell recognition of foreign Ag/MHC class II complexes is sensitive down to approximately 100 complexes per cell or approximately 0.2 complexes/micron2. To better understand the physical basis of the recognition stage of Ag presentation, we examined adhesion of the lysozyme- specific T cell hybridoma, 3A9, to artificial bilayers containing covalent MHC class II/peptide complexes or adhesion molecules. Adhesion of 3A9 cells required a superphysiologic density of the MHC class II/peptide complex and was partly dependent on CD4; cells adhered but did not crawl. No adhesion was observed to bilayers containing MHC class II molecules without the lysozyme peptide. Activated 3A9 cells adhered and crawled on bilayers containing ICAM-1. The physical strength of contacts was tested with fluid shear. 3A9 cells adherent to bilayers containing MHC class II/peptide complexes shed their contact, which remained on the substrate and contained TCR. In contrast, 3A9 cells peeled from the ICAM-1 bilayer, and held firmly on LFA-1 bilayers; in a manner dependent on filamentous actin. When ICAM-1 and the MHC/peptide complexes were combined, the 3A9 cells adhered tightly and spread, but did not crawl, on the bilayers and TCR clustered at the center of the contact area. Physiologically, the TCR is unlikely to directly initiate adhesion. TCR clusters formed with the assistance of adhesion mechanisms may have to be shed to allow de-adhesion, and this may contribute to TCR down-regulation.
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PMID:TCR-mediated adhesion of T cell hybridomas to planar bilayers containing purified MHC class II/peptide complexes and receptor shedding during detachment. 875 22

We performed immunohistochemical examinations on type II collagen-induced arthritis (CIA) mice, focusing attention on the changes in distribution of plasma proteins and extracellular matrix materials (ECM) and in expression of adhesion molecules. The limb joints of male DBA/1J mice immunized with bovine type II collagen were obtained at 6 to 20 weeks after the first immunization. In the early stage of CIA, deposition of fibrin, IgG, von Willebrand factor (vWF) and fibronectin was detected on the surface of the synovial lining layer and articular cartilage and in the articular cavity. In the stage of pannus formation, prominent proliferation of ICAM-1-positive capillaries and marked infiltration of LFA-1-positive neutrophils were observed in the pannus. The superficial portion of the pannus and basement membranes of proliferated capillaries were strongly positive for type IV collagen and laminin. In the late stage, the pannus invaded and destroyed articular cartilage and subchondral bone, and strongly positive immunostainabilities for both lysozyme and fibronectin were observed on the surface of the pannus and at the junctional portion between the pannus and the cartilage. The present immunohistochemical findings on the distribution of plasma proteins and ECM materials and the expression of adhesion molecules in CIA mice were similar to those in rheumatoid arthritis (RA) in many aspects. This suggests that CIA is a useful model for the investigation of RA.
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PMID:Immunohistochemical study on type II collagen-induced arthritis in DBA/1J mice. 935 33

The adjuvanticity of sodium houttuyfonate (SH) and its mechanism were studied in this research. Significant enhancement of antibody production was observed when co-injected with antigen. The levels of anti-BSA antibodies were measured by enzyme-linked immunosorbent assay (ELISA). The possible mechanism of this phenomenon was also investigated in this research, which included the effects of SH on the phagocytosis of macrophages, the production of lysozyme, acid phosphotase and IL-1beta generated by macrophages, the proliferation of the lymphocytes in spleen and the production of IL-2 generated by lymphocytes. IL-1beta is a co-stimulator in activating Th cells, which manifests its activity together with LFA-1, ICAM-1 and ICAM-2. These observations suggested that SH could be used as a new adjuvant.
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PMID:Studies on adjuvanticity of sodium houttuyfonate and its mechanism. 1240 Aug 71