Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.32 (bromelain)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultured mouse peritoneal cells from unstimulated mice developed plaque-forming activity against isologous bromelain-treated erythrocytes. Several IgM monoclonal autoantibodies obtained by fusion of peritoneal cells from NZB or CBA origin with BALB/c myeloma cells were purified by affinity chromatography on trimethyl ammonium (TMA) column on the basis of their cross-reactivity with TMA, phosphorylcholine (PC) or choline haptens. Binding affinity for PC hapten was of the order of 10(3) M-1. Idiotypic studies with a polyclonal rabbit anti-idiotypic reagent revealed strong cross-reactions with all hybridoma autoantibodies thus far tested. In addition, the rabbit anti-idiotypic serum detected idiotypes or cross-reactive idiotypes in the sera of NZB and CBA as well as BALB/c mice. N-terminal amino acid sequence analyses of three hybridoma autoantibodies from NZB mice and one from CBA mice were carried out. The sequences of the first 32 residues of the four heavy chains showed that three were identical while one had one amino acid interchange; they belong to the VHIII-subgroup. The light chains were identical in the first 35 residues with the exception of a substitution at position 3 in two light chains and are members of the VK-9-subgroup. These results entirely support the idiotypic data. These monoclonal autoantibodies from NZB and CBA mice although isolated and eluted from PC-related haptens do not have any apparent structural nor idiotypic relationship to PC-specific antibodies. Idiotypic and V-region N-terminal sequence data suggest that these autoantibodies constitute a highly restricted family of molecules likely to be encoded by unique germ-line genes which may be expressed as such or as somatic variants in different mouse strains.
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PMID:Monoclonal autoantibodies against mouse red blood cells: a family of structurally restricted molecules. 389 36

In a serum free, 2-mercaptoethanol supplemented culture medium muramyl dipeptide (MDP) is able to increase the number of plaque-forming cells (PFC) directed against syngeneic, bromelain-treated red blood cells (br-MRBC) and against an autoantigen, mouse albumin. The non-specific stimulation of anti-br-MRBC PFC by MDP, as by bacterial lipopolysaccharide (LPS), can be observed in spleen cell populations depleted of adherent and phagocytic cells, and in nu/nu spleen cell cultures. However, the kinetics of the induction of anti-br-MRBC PFC in murine spleen cell cultures in presence of LPS or of MDP are not identical. Moreover, MDP is able to stimulate C3H/He Orl (LPS low-responder strain) cells. Thus, the mechanisms of non-specific stimulation by MDP or by LPS could be different. Experiments done with thirteen structural analogues of MDP showed that there exists a good correlation between the adjuvant activity and the ability to induce anti-br-MRBC PFC.
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PMID:Induction of antibodies directed against self and altered-self determinants by a synthetic adjuvant, muramyl dipeptide and some of its derivatives. 616 92

Low level irradiation (400-500 R) of normal mice or of murine spleen cells resulted in the detection of an enhanced number of plaque-forming cells against bromelain-treated autologous red cells (Br MRBC) 1 day later. The mechanism responsible for the increased numbers of plaques is apparently the elimination of a suppressor T cell since the addition of thymocytes or of Lyt 1+2+ splenic cells to cultures of irradiated cells reversed the radiation-induced increase. Studies on the ontogeny of the phenomenon indicate that anti-Br MRBC plaques can be formed by spleen cells taken from mice shortly after birth although adult levels are not reached until after 3 weeks of age. Radiation-induced increases in the number of plaques were not seen until 3 weeks of age, thus, suggesting a temporal developmental sequence of the ability to produce autoantibodies and to regulate such production.
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PMID:Regulation of naturally occurring autoantibody secretion by a radiosensitive lymphocyte: initial characterization and ontogeny. 622 26

We have previously described a murine B-cell lymphoma, CH12, the cells of which bear surface IgM reactive with sheep erythrocytes (SRbc) and which could differentiate to secrete hemolytic antibody. The question addressed in this paper was whether differentiation of CH12 cells could be influenced by interaction with regulatory T cells and antigen. If so, we wanted to know whether the conditions required differed from those known to govern similar interactions with normal B cells. We had two reasons for wanting to answer these questions. First, we wondered whether CH12 could be used as a clonal population of indicator cells to study the regulation of B cell differentiation and, second, we wanted to know the extent to which these neoplastic cells were still responsive to normal regulatory signals. The first addresses a major difficulty which must be faced in studies of normal B cell differentiation: to what extent is the interpretation limited by heterogeneity of the B cells used? The second relates to the nature of neoplasia and the possibility that neoplastic cells might be rendered harmless by inducing terminal differentiation. CH12 is one of a series of transplantable B cell lymphomas which arose in B10.H-2aH-4b p/Wts (2a4b) mice, following intense immunization with SRbc. It is a monoclonal tumor, all the cells of which bear membrane IgM(kappa) of a single idiotype, reactive with sheep and chicken Rbc and with bromelain-treated autologous mouse Rbc. The cells express KkAkEk and Dd antigens appropriate to the H-2a haplotype. During the latter stages of growth in vivo or in vitro, a small proportion (less than 3%) of the cells differentiate to secrete hemolytic antibody as measured by the Cunningham assay for plaque forming cells (PFC). We cultured CH12 cells for 3 or 4 days, together with antigen and spleen cells from primed animals, and assayed for PFC induction. Differentiation was induced by spleen cells from SRbc primed 2a4b mice in the presence of SRbc or ChRbc but not rabbit or human erythrocytes. Activity was depleted by treatment of the spleen cells with anti-Thy-1 or anti-Lyt-1 but not anti-Lyt-2 plus complement. Helper cells could also be induced by priming 2a4b mice with ChRbc but not rabbit or human Rbc. Neither of these last two would induce differentiation of CH12, even when both homologous antigen and SRbc were present in the cultures.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Induced differentiation of a B cell lymphoma with known antigen specificity. 624 57

Two small plaque mutants designated as 1a and 2c were isolated from DBT cells persistently infected with the JHM strain of mouse hepatitis virus. Unlike the wild type JHM, these two mutant viruses grew more slowly with no prominent cell fusion. The buoyant densities of the mutants were slightly lower and 2c was revealed to have fewer peplomers than JHM by electron microscopy. The purified JHM contained five polypeptides with molecular weights (M.W.) of 260,000, 105,000 (GP105), 65,000, 60,000 (P60), and 23,000 (GP23). In addition to two polypeptides, P60 and GP23, which were common to JHM and the mutants, 1a was found to contain three other specific polypeptides with M.W. of 180,000 (GP180), 110,000, and 95,000 (GP95), while 2c had GP180, GP105, GP95, and one with a M.W. of 175,000. All of these polypeptides were shown to be glycosylated except for P60. After bromelain treatment, all these viruses lost the peplomers and contained P60 and another new 18,000 dalton polypeptide.
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PMID:Characterization of small plaque mutants of mouse hepatitis virus, JHM strain. 631 77

Mice were exposed in whole-body fashion to several doses of radiation and killed at various times thereafter for a determination of the number of background plaque-forming cells (PFCs) as assayed on either sheep erythrocytes or bromelain-treated autologous mouse erythrocytes. Increased numbers of both types of PFC were found in the irradiated groups. These increases were dependent on radiation dose and time after exposure. They did not appear to be caused by a disruption of normal lymphocyte traffic or a switch in immunoglobulin isotype. An increased number of PFCs on bromelain-treated mouse RBCs but not on sheep RBCs were found in irradiated congenitally athymic nude mice. On the basis of this and related observations, background PFCs on bromelain-treated mouse RBCs and on sheep RBCs appear to fall under different forms of homeostatic control.
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PMID:Effect of whole-body irradiation of mice on the number of background plaque-forming cells. 634 22

The repertoire of specificities recognized by endogenous plaque-forming cells of young or aged mice has been examined, as well as the repertoire of specificities represented by mitogen-activated B cells of those animals. Significant changes occur in both polyclonal endogenous plaque-forming cells and polyclonal B cell responsiveness, as well as reactivity for antigens expressed on bromelain-treated mouse erythrocytes and mouse Ig-coupled sheep erythrocytes. Adoptive transfer experiments suggest that these changes reflect a role for the differentiative environment in the regulation of the B cell recognition repertoire. Additional analysis of changes in antigen-presenting cells in aged mice suggest that alterations in the manner of presentation of environmental antigens in vivo may control the expressed B cell repertoire. Indeed, under experimental conditions it has proven less easy to induce B cell/macrophage restriction (for antigen presentation and induction of antibody formation) in cells of old animals than in cells of younger mice.
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PMID:Alterations in lymphocyte recognition repertoire during ageing. I. Analysis of changes in immune response potential of B lymphocytes from non-immunized aged mice, and the role of accessory cells in the expression of that potential. 638 96

After 3-5 days of in vitro culture, peritoneal cells from untreated C3H mice produce autoantibodies specific for autoantigens in the membranes of mouse erythrocytes. The autoantigens are exposed in vitro by treating mouse erythrocytes with the proteolytic enzyme bromelain. Limiting-dilution cell culture techniques were used to determine the frequency of the autoreactive B cells. Cells were cultured in Terasaki trays at 10-200 cells/well. Autoantibody production was assayed with an in situ plaque-forming cell (PFC) assay. On average, one autoantibody precursor cell was detected for every 150-200 peritoneal cells cultured. This precursor frequency was increased to 1 in 50 by the addition of lipopolysaccharide (LPS) and dextran sulphate (DS) to the culture medium. The addition of a culture supernatant from an EL4 lymphoma subline also induced a high proportion of the peritoneal cells to secrete autoantibodies. However, it was not possible to determine the frequency of PFC accurately because at limiting numbers of peritoneal cells the effects of EL4 affected more than one limiting variable. Significant cell division was observed in cultures to which LPS/DS had been added, in contrast to untreated cultures to which EL4 supernatant was added. The results show that high numbers of autoreactive B cells committed to self antigens are present in the peritoneal cavity and that these cells under the influence of appropriate cytokines can differentiate in vitro, even without proliferation, into autoantibody secretors. The cell type or types releasing the cytokines remain to be identified.
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PMID:Peritoneal B cells differentiate without proliferation into autoantibody secretors under the influence of factors released by other cells. 639 20

The development of plaque-forming cells (PFC) to bromelain-treated syngeneic mouse red blood cells (Br-MRBC) was studied in bone marrow cell (BMC) cultures. It was found that the number of marrow PFC to Br-MRBC does not show the typical spontaneous increase observed in spleen cell (SPC), or peritoneal cell (PC) cultures. The number of anti-Br-MRBC PFC was markedly increased by lipopolysaccharide (LPS), even in conditions in which cell proliferation was blocked by mitomycin C, suggesting the presence of high numbers of Br-MRBC-specific precursor cells, potentially capable of differentiating into autoantibody-producing cells, in the marrow. Moreover, the low levels of anti-Br-MRBC PFC were further reduced in the presence of concanavalin A (Con A). The addition of Con A-activated BMC to BMC, SPC, or PC cultures actively suppressed the development of anti-Br-MRBC PFC. Con A-activated BM suppressor cells were found to be Thy 1.2-negative, Ig-negative, nonadherent cells. A possible role for the BM suppressor cell in tolerance to self antigens is discussed.
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PMID:Regulation of the development of plaque-forming cells to bromelain-treated syngeneic mouse erythrocytes in bone marrow cell cultures. 641 29

The effect of tuberculin purified protein derivative (PPD) on the development of plaque-forming cells (PFC) against bromelain-treated syngeneic mouse red blood cells (Br-MRBC) was studied in peritoneal cell cultures. The finding that PPD enhances the development of PFC to Br-MRBC, even under conditions where cell division is blocked by mitomycin C treatment, suggests that cell proliferation does not represent a necessary prerequisite for differentiation of precursor cells into autoantibody-forming cells.
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PMID:Enhancement of the spontaneous development of autoreactive B cells by PPD in mouse peritoneal cell cultures. 641 66


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