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Biomedical subjects

M P Dierich

Publications and source records attributed to M P Dierich.

At least 19 recordsLinked to original sources
PubMed1992

Species specific monoclonal antibodies to Bacteroides fragilis lipopolysaccharide protect mice from severe infection.

Four monoclonal antibodies which reacted in a species specific manner with Bacteroides fragilis were isolated. They recognised at least two different epitopes of B. fragilis lipopolysaccharide. The monoclonal antibodies protected non-immune mice from longlasting bacteraemia and abscess formation induced by the intraperitoneal administration of B. fragilis in combination with an infection-potentiating agent. The monoclonal antibodies were as efficient as an anti-B. fragilis hyperimmune serum. Only antibodies administered intraperitoneally or intramuscularly were protective.

Animals↗
PubMed1979

Detection of proteolytic (C 3-cleaving) activity on mouse mastocytoma (P 815) cells and other mouse cell lines by formation of cell contact with C 3-carrying mouse lymphocytes.

Mouse mastocytoma cells (P 815) formed rosettes with normal mouse spleen lymphocytes which had been coated with uncleaved human C 3; this interaction was clearly dependent on the amount of C 3. Lymphocytes treated with C 3 b or buffer alone were ineffective. Formation of cell contact could be inhibited by the presence of protease inhibitors such as diisopropyl fluorophosphate, phenyl methyl sulfonyl fluoride and tosyllysyl chloromethyl ketone. Seve n out of 13 different cell lines behaved like P 815 cells. The results strongly suggested that a proteolytic activity on mouse tumor cells led to a cooperation with uncleaved C 3 on a carrier cell to connect these two cells. We interpreted these data in analogy to the complement-dependent bridge formation mechanism (M. P. Dierich and B. Landen, J. Exp. Med. 1977. 146: 1484): uncleaved C 3, attached to mouse spleen lymphocytes as carriers, becomes cleaved by enzymes associated with the tumor cells tested; by this cleavage, the labile binding site is released on C 3 (nascent C 3 b) and anchors the C 3-carrying cell to the protease-carrying cell; since this labile binding site is short-lived, this process can be induced by membrane-associated proteases only. The nature of the proteases and the biological implications of this process are as yet uncertain.

Animals↗
PubMed1979

Protease activity on the surface of HSV-infected cells.

Monolayers of primary rabbit kidney cells infected with HSV type I bound lymphoblastoid (Raji) cells, to which the third component (C3) of the complement system had been attached (Raji-C3). This induction of cell contact did not occur on non-infected monolayers and was dependent on C3. The interaction could be suppressed by the presence of protease inhibitors (1 mM-TLCK or-PMSF). The results are interpreted as indicating de novo expression of protease activity on the surface of HSV-infected cells. This protease is characterized by its potential to activate C3 and its inhibition by TLCK.

Animals↗
PubMed1979

Complement receptor analogous factors in human serum: I. Isolation of a molecule inhibitory for complement dependent rosette formation, its identification as alpha 1-antitrypsin and its functional characterization.

A glycoprotein was isolated from human plasma which partially inhibited C3 carrying erythrocytes from binding to complement receptor cells (CR+C). Based on its physicochemical characteristics and its antigenicity this glycoprotein was identified as alpha 1-antitrypsin (alpha 1-AT). The activity of alpha 1-AT towards C3 and its fragments was unaffected by heating but it was destroyed by periodic acid. The isolated carbohydrate moiety of alpha 1-AT showed the same effect as the intact molecule. Using F(ab)2 of IgG-anti-alpha 1-AT could be demonstrated on Raji cells and human erythrocytes. Treatment of these CR+C with IgG-anti-alpha 1-AT resulted in a blockade of their C3 receptor activity. The results suggest, that alpha 1-AT interacts through its carbohydrate portion with C3 and its fragments and functions as a complement receptor molecule.

B-Lymphocytes↗
PubMed1979

Identity of C3- and C5-receptors on lymphoid cells.

Tannic acid-treated SRBC, incubated with increasing concentrations of C5 (Etan-C5) can be attached to C3 receptor-carrying (Raji) cells. This binding is dependent on the amount of C5 on Etan-C5 and can be inhibited by pretreatment on the Raji cells with either C5 or C3. Similar inhibition by soluble C3 and C5, respectively, is obtained for the interaction between Raji cells and Etan-C3. In addition, the immune adherence reaction between Ehum and EAC1423b could be blocked by previous treatment of Ehum with C5 or C3. These results suggest the presence of binding sites for C5 on lymphoid cells and their identity with C3 receptors.

Binding Sites↗
PubMed1978

C3-mediated cytoadherence. II. Dependence of cell attachment on similar topographic distribution of the receptors (for C3) and the ligands (C3/C3b).

Particles carrying C3 in a random distribution (Etan-C3) bound to C3 receptor (Raji+) cells independent of temperature and irrespective of whether the Raji cells were fixed with glutardialdehyde. In contrast, the reactivity of EAC43b, having grouped C3b in clusters, was dependent on temperature. The interaction with Raji cells was inhibited if the latter were treated with a fixative. The reaction of both Etan-C3 and EAC43b was a function of the concentration of C3 and C3b, respectively. The conclusion is drawn that for the interaction between C3/C3b-carrying particles and C receptor cells the receptors and the ligands have to be grouped in a similar typographic distribution, irrespective if this arrangement is provided already from the beginning or if it is obtained only by lateral movement of one or both reaction partners.

Animals↗
PubMed1977

Complement bridges between cells analysis of a possible cell-cell interaction mechanism.

Different leukocytes (Raji, Daudi, Rael lymphoid cells; human peripheral blood lymphocytes, and guinea pig granulocytes), which had been coated with C3 by incubation of 37 degrees C for 20 min in a C3 solution, were demonstrated to form rosettes with erythrocytes coated with complement components (EAC142). The percentage of rosettes was dependent of the amount of C3 present on the cells. Loading of the lymphoid cells with C3 was a time- and temperature-dependent process. C3b was unable to serve the same purposes, although C3 and C3b occupied the C3 receptors on the lymphoid cells to a comparable degree. C3 functions in a similar manner. The C42 enzyme can be replaced by trypsin, so that bridging units may consist of C3 + C42, C5 + C42 OR C3 + trypsin, and C5 + trypsin. Bridging units can be constructed also from C4 + C1. It is suggested that enzymes on one cell liberate labile binding groups of complement components on adjacent cells, thus inducing coupling of the two cells. The possibility is raised that this type of cell interlinkage may play a role in vivo, since there is accumulating evidence that complement components are expressed in the plasma membrane of different cells.

Cell Communication↗
PubMed1977

K cell activity of normal and chronic lymphocytic leukaemia lymphocytes: association with lymphocytes bearing receptors for human C3b.

Blood lymphocytes of patients with chronic lymphocytic leukaemia (CLL) and of normal individuals were depleted of EAC3b- or EAC3d-rosette-forming cells (RFC), respectively and assayed for K-cell activity in a system measuring antibody-dependent-cell-mediated cytotoxicity (ADCC). K-cell activity was found to be associated with a cell population bearing receptors for C3b.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1977

K-lymphocytes (killer-cells) in Crohn's disease and acute virus B-hepatitis.

Total lymphocyte counts, B-, T-, C'3 receptor-bearing lymphocytes, and K-cell activity were studied in peripheral blood in patients with Crohn's disease and inflammatory liver disease. Patients with active untreated Crohn's disease and acute virus B hepatitis exhibited a markedly increased K-cell activity measured in a plaque assay when compared with normal controls (P less than 0.01). Patients with immunosuppressive treated Crohn's disease, HBsAg-positive chronic active hepatitis, and cirrhosis of the liver showed only a slight increase of K-cell activity (P less than 0.01). In the postacute phase of hepatitis (four to 12 weeks from onset) K-cell activity fell to normal levels. The number of B-lymphocytes showed a relative and absolute decrease in all groups of patients. With the exception of patients with acute HBsAg-positive hepatitis and the post-acute phase of hepatitis all the other groups showed statistically decreased absolute numbers for C'3 receptor-bearing lymphocytes. The significant decrease in K-cell activity and the number of T-lymphocytes in Crohn's disease treated with immunosuppressive drugs was interpreted as an effect of azathioprine and prednisone on these lymphocyte subpopulations.

Acute Disease↗
PubMed1977

Receptor-binding sites on C3 and C3b.

Human erythrocytes carry C3b receptors: Daudi lymphoid cells carry exclusively C3d receptors. With these two types of cells, it could be shown that isolated, uncleaved human C3 and soluble C3b possess two stable binding sites: SBS1-specific C3b receptors, and SBS2-specific for C3d receptors. Upon binding of freshly cleaved C3b (nascent C3b) via its labile binding site (generated on C3b through cleavage of C3) to the C3 acceptors on cell surfaces, the SBS2 becomes concealed. Kinetic experiments show that immediately after the action of fetal calf serum or partially purified C3b-inactivator on EAC1423b the SBS2 is accessible again. The reappearance of SBS2 does coincide with cleavage of surface-bound C3b into C3c and C3d but not with the release of C3c from the cell; C3c remains attached and is released only with delay. Concomitant with the cleavage event the number of SBS1 is reduced, stressing the importance of an unaltered steric configuration of the C3b structure for the expression of SBS1. An alternative explanation might be that the SBS1 is located at the site connecting C3c and C3d, so that it becomes altered upon dissection of the two fragments.

Binding Sites, Antibody↗
PubMed1976

Demonstration of binding sites for IgG Fc and the third complement component (C3) on isolated hepatocytes.

Isolated hepatocytes from rabbits with experimental acute serum sickness showed immune complexes bound to the hepatocellular membrane with a coarse granular fluorescent pattern. Also in vitro preformed immune complexes (BSA-anti-BSA) or aggregated gamma-globulin from human and rabbit could be bound to the surface of isolated hepatocytes. In contrast, immune complexes with F(ab')2 anti-BSA were not fixed on the membranes. Hepatocytes incubated in fresh serum showed membrane-fixed C3 in a coarse granular pattern. This deposition could be abolished by heating (56 degrees C, 30 min) the serum or by adding EDTA (0.02 M). Also, purified human or guinea pig C3 could be bound to the hepatocellular membrane but in a linear fluorescent pattern. Thus, fixation of immune complexes on hepatocytes appears to operate through binding sites for IgG Fc and, possibly, also through binding sites for C3. It is suggested that these hepatocellular-binding sites may have a physiologic clearance function. In vivo fixed IgA could be detected on the membranes of isolated hepatocytes from healthy persons. It is assumed that the membrane-fixed IgA has a carrier function for antigens from the gut.

Animals↗
PubMed1975

C3-mediated cytoadherence. Formation of C3 receptor aggregates as prerequisite for cell attachment.

Inhibition of free movement of C3 receptors by either applying low temperature (3 degrees C) or fixing the cell surfce of lymphocytes with glutaraldehyde (2 times 10(-5) to 2 times 10(-1)%) results in loss of firm attachment of EAC142 3b cells to the lympocytes as demonstrated here by loss of rosette formation of Raji lymphoid cells. Under the same conditions soluble C3 can still bind but is unable to induce aggregation of C3 receptors into small patches. It is suggested that the local increase of C3 receptor density by aggregation is a prerequisite for C3-dependent cytoadherence. Microaggregation of corresponding receptor sites may be essential also in other recognition systems.

Animals↗