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:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MHC class II molecules are involved in the presentation of both exogenous and endogenous antigens to CD4 T cells. Using the trans-membrane hemagglutinin (HA) from measles virus and the secreted hen egg lysozyme (HEL) as antigen models, we have compared the efficiency of MHC class II presentation by naive antigen presenting cells (APCs) pulsed with exogenous antigen with that of their transfected counterparts synthesizing endogenous antigen. B cells expressing even a very low amount of trans-membrane HA were found to present endogenous HA to I-Ed restricted T cell hybridomas with a high efficiency whereas their naive counterparts required to be pulsed with a comparatively high amount of exogenous HA. Similarly, MHC class II presentation of endogenous secreted HEL was found to be much more efficient when compared with that of exogenous HEL. Biochemical studies did not reveal any enhanced intracellular degradation of endogenous HEL. As expected, HEL was released in the surrounding medium within < 1 h. MHC class II presentation of endogenous HEL could not be explained by re-uptake by bystander APCs of HEL secreted in the surrounding medium. No sensitization of naive APCs could be observed either when co-cultured with HEL secreting cells or when cultured for 10 days with a sub-threshold amount of exogenous HEL. At the cell surface, I-Ed molecules immunoprecipitated from HEL secreting cells were found to be slightly enriched in SDS-resistant forms. These data raised the question of how peptides derived from endogenous transmembrane and secreted antigens can so efficiently reach an MHC class II loading compartment.
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PMID:High efficiency of endogenous antigen presentation by MHC class II molecules. 133 77

In this study we investigated the role of the invariant chain (li) in the presentation of hen egg lysozyme (HEL) and measles virus hemagglutinin (HA) antigens to MHC class II-restricted T hybridoma cells. Fibroblastic cells transfected with Ed or Ak genes, and supertransfected or not with the li gene, were used as antigen-presenting cells (APC). For every APC pair analysed, the amount of exogenous antigen needed to obtain a T-cell response was inversely correlated with the level of li expression. Exogenously provided HEL was efficiently presented by li-supertransfected APC at doses of 10 micrograms/ml or below. In contrast, non-li transfected fibroblastic cells, which express a low level of endogenous li, required at least 10 times more HEL to stimulate most of the T hybridoma cells. Analogous results were also obtained using exogenous HA. Finally, two different experiments suggest that basal li expressed in fibroblastic cells is involved in the presentation of exogenous antigen. In the first one, we showed that li/class II ratio was increased in high-density grown fibroblastic cells and that this increase correlates with the ability of the cells to present exogenous antigen. In the second, treating high-density grown cells with an antisense li oligodeoxynucleotide could impair their ability to present exogenous HEL. We also examined the presentation of endogenously-synthesized HEL or HA after introduction of the antigen into the biosynthetic pathway of the APC by transfection of HEL and HA cDNAs. There was no apparent difference in the capability of high density grown fibroblastic cells, transfected or not with li gene, to present endogenous HEL or HA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Correlation between invariant chain expression level and capability to present antigen to MHC class II-restricted T cells. 165

We report a case of infantile acute leukemia with t(16; 21) (p11; q22). The patient was a phenotypically normal one-year-old girl without lymphadenopathy or hepatosplenomegaly. Her peripheral blood at diagnosis showed anemia, thrombocytopenia, and many circulating blasts. Bone marrow blasts were monocytoid with fine reticular nuclear chromatin, abundant grayish-blue cytoplasm with occasional pseudopods or cytoplasmic projections and active hemophagocytosis. Serum levels of lysozyme and ferritin were normal. These blasts were not stained with butyrate esterase and immunologic study showed KOR-P77+ (anti-megakaryocyte monoclonal antibody), MY9+, Ia-. Electron microscopic examination failed to show platelet peroxidase activity. Remission was not induced by mini-COAP or VP-16 and the patient died of measles pneumonitis. The patient's blasts took typical appearance of megakaryoblasts later in the course, although some of them retained the ability of hemophagocytosis observed in the original blasts. This case is considered to be quite atypical since leukemic cells with active hemophagocytosis, megakaryoblastic appearance and t(16; 21) (p11; q22) have not been reported in the literature.
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PMID:[Acute leukemia with active hemophagocytosis, positive immunologic markers for the megakaryocyte-platelet lineage, and translocation (16; 21) (p11; q22]. 231 8

We tested the effect of lysozyme on the nasal mucosa in a controlled double-blind in vivo study. The administration of non-pathogenic vaccine strains of living measles virus and of living Vivotif bacteria (attenuated Salmonella typhi) to 14 healthy subjects showed that lysozyme possesses a clear antimicrobial and antiviral effect.
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PMID:[The antimicrobial effect of lysozyme on nasal mucosa]. 265 60

The current state of knowledge of lung defenses has been reviewed. First, mechanical factors such as aerodynamic filtration and mucociliary transport were considered. Then, in general terms, the contributions of alveolar macrophages, neutrophils, lymphocytes, and immunoglobulins, and the roles of complement, antiproteases, lysozyme, and fibronectin were examined. Interactions between these components may regulate their effect. Finally, the responses to five specific microorganisms were reviewed to illustrate different aspects of the lung's defenses. Streptococcus pneumoniae was selected as a representative extracellular bacterial pathogen, Mycobacterium tuberculosis as an intracellular bacterial pathogen, Mycoplasma pneumoniae because it elicits significant humoral and cell-mediated immunity, respiratory syncytial virus as an example of a local viral pathogen, and measles as a viral pathogen that causes generalized disease. It was shown that these responses may not always be beneficial for the host. For each of the five infections, recommendations for improving the outcome were made.
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PMID:Lung defenses against infection: a clinical correlation. 634 46

Chloroquine treatment of antigen-presenting cells (APC) was explored as a tool to investigate the processing pathway for major histocompatibility complex (MHC) class II-restricted presentation of the endogenous secreted hen egg lysozyme (HEL) and transmembrane measles virus haemagglutinin (HA). A 72-hr pretreatment of the APC with 25 microM chloroquine blocked the presentation of the HEL(52-61) T-cell epitope generated from endogenous HEL to the I-Ak-restricted 3A9 T-cell hybridoma by MHC class II-transfected L cells expressing the invariant chain (Ii). The presentation of exogenously added HEL peptides was not affected. Under the same conditions, no inhibition of the presentation of HEL(106-116) to the I-Ed-restricted G28 high-avidity T-cell hybridoma, nor of HA when synthesized by L cells, was observed. When B-lymphoid APC were used, inhibition was observed in every case with a low number of B APC pretreated for 48 hr with chloroquine prior to the T-cell stimulation test. Moreover, addition of chloroquine to untreated B APC during the T-cell stimulation assay was sufficient to inhibit completely the presentation of HEL(106-116) to the B10.D24.42 low avidity T-cell hybridoma. Altogether these studies suggest that an apparent resistance of endogenous Ag presentation to chloroquine inhibition may not necessarily indicate the existence of a non-endosomal pathway but may be due to the nature of the T-cell epitope, to the use of 'non-professional' APC such as L cells, to the use of T cells of high avidity, and to high amounts of pre-existing MHC class II-peptide complexes expressed by the APC. We demonstrate here that, at least in conventional APC such as B cells, class II-restricted presentation of both endogenous secreted HEL and transmembrane HA involves an endosomal pathway.
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PMID:Inhibition by chloroquine of the class II major histocompatibility complex-restricted presentation of endogenous antigens varies according to the cellular origin of the antigen-presenting cells, the nature of the T-cell epitope, and the responding T cell. 750 20

I-Ak- and I-Ed-transfected L fibroblasts were supertransfected with cDNA coding for hen egg lysozyme (HEL) or measles virus hemagglutinin (HA). Well-defined cell culture conditions allowed us to obtain L cells with either no detectable endogenous Ii mRNA or a high level of endogenous Ii mRNA induced by serum starvation. Cells supertransfected with mouse Ii chain gene stably expressing a high level of Ii chain were also used as APC in parallel experiments. Class II presentation of endogenously secreted HEL or an ER-retained form of HEL to the HEL-specific I-Ak-restricted 3A9 T cell hybridoma was found to be strongly enhanced in cell transfectants expressing Ii chain. Similar results were obtained with the presentation of transmembrane HA to the HA-specific I-Ed-restricted TH5.143 T cell hybridoma. These findings correlate with those obtained with the presentation of exogenous HEL and HA. In addition, as reported to be the case for exogenous antigen, expression of a large amount of endogenous HA by the APC supplants the requirement for Ii chain expression in the enhancement of antigen presentation. These data demonstrate that presentation by MHC class II molecules of a given antigen, either exogenously provided or endogenously synthesized, is controlled in a similar manner by the Ii chain.
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PMID:Invariant chain expression similarly controls presentation of endogenously synthesized and exogenous antigens by MHC class II molecules. 849 91

CD46 (membrane cofactor protein) is a human cell-surface regulator of activated complement and a receptor for the measles virus. A CD46 transgenic mouse line with an expression pattern similar to that of human tissues has been produced, to develop an animal model of (i) the control of complement activation by complement regulators in hyperacute rejection of xenografts, and (ii) measles virus infection. The mouse line was made using a CD46 minigene that includes promoter sequence and the first two introns of genomic CD46, which was coinjected into mouse ova with chicken lysozyme matrix attachment region DNA. A high level of CD46 expression in homozygotic transgenic mice was obtained with spleen cells having approximately 75% of the level found on human peripheral blood mononuclear cells. CD46 was detected in all tissues examined by immunohistochemistry, radioimmunoassay and Western blotting, showing that these mice were suitable for transplantation and measles virus infection studies. It also indicated that the transgene included the important regulatory elements of the CD46 promoter. Transgenic spleen cells were significantly protected in vitro from human complement activated by either the classical or alternative pathways and from alternative pathway rat complement. Furthermore, transgenic mouse hearts transplanted to rats regulated complement deposition in an in vivo model of antibody-dependent hyperacute xenograft rejection. Similar to human lymphocytes, transgenic lymphoblasts could be infected in vitro with measles virus; infected cells expressed viral proteins and produced infectious viral particles. The data demonstrate the suitability of this minigene for obtaining high-level CD46 expression sufficient for enhanced resistance of transgenic cells to complement attack and for obtaining wide tissue distribution of CD46, analogous to human tissues and, therefore, useful for comparative studies.
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PMID:Transgenic expression of a CD46 (membrane cofactor protein) minigene: studies of xenotransplantation and measles virus infection. 907 15

The paper outlines the results of studies dealt with the detection of risk factors and groups for enterobiasis, the efficiency of the treatment of children suffering from the disease with medamine, biologicals, and Normase. It is shown that risk factors may include an abnormal course of antenatality, minor developmental malformations (diastema, dystrophy, abnormalities of the eye, hand, foot, etc.), as well as early artificial feeding of babies (before they reach 3 months of life). Enterobiasis is found to have a negative influence on the physical, nervous, and mental development and suppression of non-specific immunity in children, which is suggested by the reduction in salivary lysozyme activity, which is lower than the normal level and on blood alpha-interferon production. There is strong evidence for the considerable immunosuppressive effects of enterobiasis on the formation of a postvaccinal immunity against measles. When given in a single course dose, medamine shows a 100% efficiency in the treatment of enterobiasis. Moreover, bificol, bifidumbacterin, and Normase may be useful to enhance the treatment efficiency and children's recovery from enterobiasis.
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PMID:[New approaches to the eradication of enterobiasis in children]. 918 91

Iron deficiency and diarrhea are two of the most significant issues for global health. Iron deficiency anemia is the most common nutritional deficiency in the world, affecting nearly 25% of the world population (UNICEF/WHO 1999). The prevalence of iron deficiency in developing countries is illustrated by comparison with other deficiencies: iron deficiency affects 3.5 billion people, while vitamin A and iodine deficiency affect 0.3 billion people and 0.8 billion people, respectively. The prevalence is highest among young children and women of childbearing age (particularly pregnant women). It is estimated that national productivity levels could be raised as much as 20% by correcting iron deficiency in developing countries. Recombinant human lactoferrin (rhLF), expressed and extracted from rice seed, is being evaluated by Ventria Bioscience for use as a dietary supplement to treat iron deficiency and/or iron deficiency anemia. Diarrhea is also a major world health issue. Sixty percent of children who die under age five die of pneumonia, diarrhea or measles. World Health Organization oral rehydration solution (WHO-ORS) is one of the major medical advances in the past 50 years, saving the lives of 1 to 2 million children annually. Many studies have demonstrated similar efficacy of rice-based ORS. There are studies documenting the reduced frequency of diarrhea in breast-fed children and this health improvement is attributed to the antimicrobial action of the human milk proteins lactoferrin and lysozyme. In vitro data document the growth inhibition of the diarrheal associated organisms: rotavirus, ETEC, cholera, salmonella, and shigella by human lactoferrin (hLF) and human lysozyme. Using Ventria's ExpressTec system, we have expressed human lactoferrin and human lysozyme in rice. In a rice-based ORS formulation, these proteins have the potential to provide not only the benefits of reduced stool volume and improved weight gain, but also shorten the course of diarrheal episodes via antimicrobial activity against the causative agent.
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PMID:Recombinant human lactoferrin treatment for global health issues: iron deficiency and acute diarrhea. 1522 87


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