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K Whaley

Publications and source records attributed to K Whaley.

At least 55 records · Page 3Linked to original sources
PubMed1990

Interferon-induced transcriptional and post-transcriptional modulation of factor H and C4 binding-protein synthesis in human monocytes.

Cultured human monocytes synthesize factor H (H) and C4 binding protein (C4-bp), as assessed by measuring their presence in culture fluids, and demonstrating the presence of their corresponding mRNAs in total monocyte RNA by Northern blot analysis and by nuclear run-on experiments. H mRNA (4.3 kb and 1.8 kb) could only be detected when cycloheximide (2.5 micrograms/ml) was present in monocyte culture fluid. Recombinant interferon-gamma (IFN-gamma) and lymphoblastoid interferon-alpha (IFN-alpha) produce dose-related increases in the synthesis of H and C4-bp and in the abundance of C4-bp mRNA (2.5 kb). Increased abundance of H mRNA was also seen when cycloheximide (2.5 micrograms/ml) was present in the cultures. Both cytokines increased the transcription rates of the H and C4-bp genes. These changes in transcription were rapid, with significant increases being observed within 30 min of exposure. Following the removal of the cytokines from the cultures the transcription rates of both genes returned to control levels within 4 h. The effects of combining IFN-alpha and IFN-gamma on H and C4-bp transcription rates, mRNA abundances and protein secretion rates were not quantitatively additive. The half-life of H mRNA in monocytes was 15 min, whereas that of C4-bp mRNA was 2 h 45 min. Neither half-life was altered by IFN-gamma.

Carrier Proteins↗
PubMed1990

Modulation by interferons of the expression of monocyte complement genes.

Interferons-alpha, -beta and -gamma (IFNs-alpha, -beta and -gamma) stimulated the synthesis of the second complement component (C2), Factor B (B) and C1 inhibitor (C1-inh) by human monocytes in vitro. The degree of increase of the secretion rates of C2, B and C1-inh was dose-dependent and proportional to increases in the abundances of their respective mRNAs. IFN-gamma was the most effective at stimulating monocyte C1-inh synthesis, whereas IFN-alpha and IFN-beta were marginally more effective at stimulating monocyte C2 and B synthesis. Kinetic studies showed that the effect of the IFNs was rapid, with maximum stimulation occurring within 1-2 h for all three proteins. After the removal of IFNs from cultures the C1-inh mRNA abundance remained elevated for over 24 h in IFN-gamma-treated monocytes but returned to control levels within 8 h in IFN-alpha-treated and IFN-beta-treated monocytes. The abundances of C2 mRNA and B mRNA also returned to basal values within 8 h after removal of any of the three cytokines from the cultures. Both IFN-alpha and IFN-beta acted synergistically with IFN-gamma to stimulate synthesis of C1-inh and B. This synergistic effect only occurred when the cytokines were present in the cultures simultaneously. The effects of IFN-gamma plus IFN-alpha or IFN-beta on C2 synthesis appeared to be additive rather than synergistic. IFN-gamma inhibited synthesis of C3 by monocytes, but IFN-alpha and IFN-beta had no effect on the synthesis of this protein. Furthermore, none of the three cytokines had any effect on the expression of actin mRNA in monocytes.

Cells, Cultured↗
PubMed1990

Measurement of complement activation products in patients with chronic rheumatic diseases.

Measurement of the complement activation products C1s:C1-inh, C3bP and C5b-9 by ELISA in plasma samples from normals, rheumatoid arthritis (RA) and systemic lupus erythematosis (SLE) patients showed significantly elevated levels in the two patient groups (P less than 0.0001 for C1s:C1-inh, C3bP and C5b-9) compared to normals. In seropositive RA patients there were significant correlations between the levels of the three complement activation complexes and IgM-RF, IgG-RF and IgA-RF. However, IgM-RF did not interfere with any of the ELISA systems. Mean levels of C1s:C1-inh, C3bP and C5b-9 were the same in paired plasma and synovial fluids; however, C3bP levels in the paired samples did not correlate with one another by rank. Our conclusions are that: (a) elevated plasma levels of these complement activation products are detectable in rheumatic diseases; (b) plasma levels of these complement activation products are related to Rheumatoid factor (RF) levels in seropositive RA patients; and (c) IgM-RF does not influence these solid-phase ELISA procedures.

Antibodies↗
PubMed1990

The effect of antibody isotype on the activation of C3 and C4 by immune complexes formed in the presence of serum: correlation with the prevention of immune precipitation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement during the formation of immune complexes in human serum by the interaction of DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. Those containing IgG2 or IgM were potent activators of C4, whilst IgG1 containing complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. All complexes except those containing IgA precipitated more slowly in serum than in buffer. IgG2 antibodies were potent activators despite being very slow to precipitate in buffer. In serum containing EGTA activation of C4 was abolished and precipitation of complexes occurred at the same rate as in buffer. Nevertheless, C3 activation still occurred by the alternative pathway for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. The ranking of the ability to activate complement was the same as that observed when performed complexes containing the same antibodies were added to serum. The levels of C4a generated were similar under both conditions but for most antibodies more C3a was generated by preformed complexes.

Antibodies, Monoclonal↗
PubMed1990

Immunohistochemical localization of a plasma protein (glycoprotein 60) which inhibits complement-mediated prevention of immune precipitation.

Using various immunocytochemical techniques it has been shown that glycoprotein 60 (gp60), an IgG Fc-binding protein recently isolated from normal human plasma, is found localized in human hepatocytes, platelets and a subpopulation of normal peripheral blood lymphocytes (PBL). This protein, which appears to be identical to a 60,000 MW IgG-binding protein (60-IBF) previously isolated from normal human PBL culture supernatants, also appears to be distinct from the three well-defined leucocyte Fc gamma-receptors: Fc gamma RI, Fc gamma RII and Fc gamma RIII.

Antigens, CD↗
PubMed1990

Mechanism of action of an inhibitor of complement-mediated prevention of immune precipitation.

Glycoprotein 60 (gp60) is a normal plasma protein (mean concentration in normal serum 34 micrograms/ml) that is present in increased levels (mean concentration 97 micrograms/ml) in the sera of patients with rheumatoid arthritis (RA). Purified gp60 binds to IgG but not to IgM, and competitively inhibits the binding of C1q. In fluid-phase studies, purified gp60 was shown to reduce immune complex-mediated complement activation in a dose-dependent manner. The addition of Fab anti-gp60 to normal serum was associated with (i) increased levels of complement-mediated prevention of immune precipitation (PIP); (ii) increased total haemolytic complement activity when EAIgG, but not when EAIgM, were used as targets; and (iii) increased immune complex-mediated complement activation. Thus gp60 appears to regulate immune complex-mediated classical pathway activation. The findings that Fab anti-gp60 (i) only partly restored PIP in RA sera showing reduced PIP levels and (ii) only partly reduced inhibition of PIP by RA sera, show that gp60 is not entirely responsible for these abnormalities.

Antigen-Antibody Complex↗
PubMed1989

Regulation of hepatic synthesis of C3 and C4 during the acute-phase response in the rat.

Following the i.p. injection of casein, rats showed increased serum levels of C4 and C3. C4 levels peaked on day 2 and returned to normal by day 4, while C3 levels peaked on day 3 before returning to normal on day 4. These changes were paralleled by changes in the hepatocyte synthesis rates of these two proteins. Macrophages, isolated from the peritoneal cavities of rats on days 1 to 7 (day-1 to day-7 macrophages) following i.p. injection of casein, were cultured in vitro, and the peritoneal macrophage-conditioned media (PMCM) assayed for their abilities to stimulate synthesis of C4 and C3 by hepatocytes from control rats. Day-2 PMCM selectively stimulated synthesis of C4, while day-3 and day-4 PMCM selectively stimulated C3 synthesis. These activities were called C4-hepatocyte stimulating factor (C4-HSF) and C3-HSF, respectively. The addition of anti-interleukin (IL) 1, tumor necrosis factor (TNF)-alpha, TNF-beta, IL 6 or interferon (IFN)-gamma antibodies to day-2 PMCM did not affect C4-HSF activity, and none had any effect on C3-HSF activity in day-4 PMCM. However, the addition of anti-IL 1 to day-4 PMCM resulted in the re-expression of C4-HSF activity as well as loss of thymocyte proliferative activity. C4-HSF activity could also be detected in day-4 PMCM by separating it from IL 1 activity using gel filtration chromatography. Furthermore the addition of recombinant IL 1 beta to day-2 PMCM prevented the expression of C4-HSF activity. Thus IL 1 appears to play a regulatory role in the acute-phase response in the rat, by preventing the expression of C4-HSF activity. The identities of C4-HSF activity and C3-HSF are still unknown but we believe that C3-HSF activity could be IL 6 as it has a similar molecular weight (30 kDa) and purified human IL 6 was more effective than IL 1, TNF-alpha or TNF-beta in stimulating C3 synthesis by rat hepatocytes. C4-HSF activity appears to be a property of a previously undescribed cytokine. It is not IL 1 alpha or beta, TNF-alpha or -beta, IL 6 or IFN-gamma.

Acute-Phase Reaction↗
PubMed1989

Complement and related clinical disorders.

The complement system, composed of 20 plasma proteins and several membrane receptors, plays an essential role in humoral immune responses. The activation of the classical and/or alternative pathways by specific and non-specific stimuli leads to the generation of chemotactic and anaphylatoxic inflammatory mediators, the formation of the cytolytic membrane attack complex, and the formation of C3 breakdown fragments which are opsonic. There is now evidence that the membrane receptors play important immunoregulatory functions. The link between various disease states and deficiencies of complement components and membrane receptors further supports the important immunological role this system plays. This review briefly introduces the components of the system, their biological roles and diseases associated with deficiency states.

Complement System Proteins↗
PubMed1989

Monocyte C1-inhibitor synthesis in patients with C1-inhibitor deficiency.

Monocytes of seven out of eight patients with type 1 C1-inhibitor (C1-inh) deficiency (HAE) produced 40% as much C1-inh as monocytes from normal donors (controls). In contrast, monocytes from three patients with type 2 and three patients with acquired C1-inh deficiency produced similar amounts of C1-inh as controls. Recombinant gamma-interferon (gamma-interferon 10 ng/ml) stimulated C1-inh production of C1-inh (eight-10-fold) by control and patients' monocytes. Monocytes from patients with type 1 HAE contained 40% the level of C1-inh messenger ribonucleic acid (mRNA) found in control monocytes. Gamma-interferon increased the abundance of C1-inh mRNA by the same extent in both control and patients' monocytes. C1-inh protein and mRNA were undetectable in the monocytes of one patient, unless stimulated by gamma-interferon. Under these conditions, his monocytes produced comparable amounts of C1-inh (protein and mRNA) as gamma-interferon-stimulated monocytes of the other type 1 HAE patients. The data suggest that in most type 2 HAE patients there is a lesion in the C1-inh gene such that mRNA is transcribed by a single allele.

Angioedema↗
PubMed1989

Measurement of complement activation in clinical practice.

Many new tests which measure complement activation are now available, although it is unclear which tests or group of tests are appropriate for monitoring complement activation in clinical samples. Carefully planned prospective studies are required to resolve this issue, and to identify which groups of patients in which the monitoring of complement activation improves the quality of their medical management.

Clinical Laboratory Techniques↗
PubMed1989

Autoantibody facilitated cleavage of C1-inhibitor in autoimmune angioedema.

C1-inhibitor (C1-Inh) is an important inhibitor of the inflammatory response and deficiency of this inhibitor, which may be hereditary or acquired, is associated with recurrent episodes of edema. Recently, an autoimmune form of angioedema has been described that is associated with functional deficiency of C1-Inh and an autoantibody that impedes C1-Inh function. In this report we describe the isolation of C1-Inh from the monocytes and plasma of a patient with autoimmune angioedema and demonstrate that the patient's monocytes secrete structurally and functionally normal C1-Inh, but show that this protein circulates in the patient's plasma in an inactive, structurally altered form. Furthermore, using analytic gel electrophoresis techniques it is demonstrated that the patient's autoantibody facilitates cleavage of normal C1-Inh, by its target proteases, to the same species of C1-Inh that is found circulating in the patient's plasma. This autoantibody facilitated cleavage of normal C1-Inh is apparently a consequence of destabilization of protease/inhibitor complexes. These findings contribute to our understanding of protease/C1-Inh interactions and document important observations on pathogenic mechanisms in autoimmune disease.

Angioedema↗
PubMed1989

The plasma protein which inhibits complement-mediated prevention of immune precipitation is an Fc binding protein.

A glycoprotein (gp60) that inhibits complement-mediated prevention of immune precipitation (PIP) has been purified from normal serum. [125I]gp60 binds to IgG but not to IgA or IgM. The binding site has been shown to be localized on the Fc piece. The binding of radiolabelled gp60 to IgG has been analysed by direct binding and Scatchard, double-reciprocal and Hill plots. The mean affinity constant of gp60 for IgG is 1.56 x 10(8) l/mol and there appears to be a single class of binding sites for gp60 on IgG. Saturation was achieved when one molecule of gp60 was bound to each molecule of IgG. In competition inhibition assays, gp60 was shown to compete with C1q and IgM and IgG rheumatoid factors. The ability to inhibit C1q binding suggests that gp60 inhibits PIP by preventing binding and activation of C1. The possibility that gp60 is a fluid-phase Fc gamma receptor is discussed. See also the note added in proof.

Binding Sites↗
PubMed1989

Regulation of C1-inhibitor synthesis by interferons and other agents.

C1-inhibitor (C1-inh) is synthesised and secreted by at least four cell types: hepatocytes, mononuclear phagocytes, fibroblasts and umbilical vein endothelial cells. The production of this protein by monocytes/macrophages and Hep G2 cells has been studied in great detail. Environmental factors alter C1-inh synthesis by these cells. A number of agents which inhibit monocyte C1-inh production (such as histamine, PGE2 C5a des arg and serum treated immune complexes) bind to membrane receptors, activate adenylate cyclase, elevate intracellular cAMP and activate cAMP-dependent protein kinase. Elevation of monocyte cAMP levels is associated with decreased C1-inh secretion by these cells and reduced C1-inh mRNA levels. These changes can be seen within 8 hours of exposure. Stimulation of monocyte C1-inh synthesis occurs after the addition of agents which induce the formation of sodium ion and calcium ion channels, activate the phosphatidyl inositol cycle and activate protein kinase C (immune-complexes, carbamylcholine and phenylephrine). Agents which act directly on protein kinase C (phorbol myristate acetate) also stimulate C1-inh synthesis. Amongst the most potent stimulators of monocyte and Hep G2 C1-inh synthesis are the interferons (Ifns) Ifn alpha, Ifn beta and Ifn gamma. These are known to bind to specific receptors on cells (Ifn alpha and beta binding to Type I Ifn receptors and Ifn-gamma binding to type II Ifn receptors). At least two mechanisms by which Ifn receptor-ligand interaction elicit their effects exist. These are: 1) binding of an activated receptor transducer/regulatory component to specific DNA sequences on Ifn sensitive genes; 2) the activation of protein kinase C and binding of its regulatory components to specific DNA sequences. Ifn alpha, beta and gamma cause a dose related increase in monocyte and Hep G2 cell C1-inh mRNA abundance and protein synthesis. Ifn-gamma is the most potent of the interferons on monocyte C1-inh synthesis. Ifn alpha and beta being less effective but equipotent. These cytokines elicit their maximum effect on monocyte C1-inh synthesis after 1-2 hours treatment. This rapid stimulation of monocyte C1-inh synthesis suggests that this increases the transcription of the C1-inh gene. After removal of Ifns from monocytes the elevated C1-inh mRNA levels subside towards control levels of expression in Ifn alpha and beta-treated cells but remain elevated in Ifn-gamma-treated monocytes. This binding suggests that Ifn-gamma alters the stability of C1-inh mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)

Carcinoma, Hepatocellular↗
PubMed1989

Modulation of monocyte complement synthesis by lymphocytes and lymphocyte-conditioned media.

Culture supernatants from mitogen- and antigen-stimulated human peripheral blood lymphocytes (PBL), stimulated synthesis of the second complement component (C2) by human monocytes, but not as effectively as the stimulated PBL themselves, which adhered to the monocytes and caused marked spreading. In contrast to PBL, lymphocytes isolated from the synovial membranes (SML) of patients with rheumatoid arthritis and their culture supernatants were able to stimulate C2 synthesis without exposure to mitogens or antigens. Depletion of B and T populations showed that T cells were responsible for stimulation of C2 synthesis. Further studies of synthesis rates of C2, C3 factor B (B), C1 inhibitor, and properdin (P) were undertaken, and it was found that lymphocytes and their supernatants increased synthesis of C2, B and C1 inhibitor, and reduced synthesis of C3 and P. This profile of activity was identical to that produced by the addition of recombinant gamma-interferon (rIFN-gamma) to the cultures. Furthermore the addition of a monoclonal antibody to rIFN-gamma to cultures abrogated the effects of rIFN-gamma, and almost completely reversed the effects of lymphocytes and their supernatants. Thus it appears that gamma-interferon is the lymphocyte product which is responsible for the modulation of monocyte complement synthesis. The results of studies with synovial membrane lymphocytes raise the possibility that this process occurs in vivo. Monocyte C2 had a higher specific functional activity (SpFA) than serum C2 isolated from serum or C2 produced by HepG2 cells. Monocyte C2 formed a C3 convertase which had a longer half-life than that found with both serum C2 or HepG2 C2. Thus monocyte C2 behaves like oxidized C2. Monocytes exposed to rIFN-gamma, lymphocytes or lymphocyte-conditioned medium (LCM) produced C2 which had an even higher SpFA. Although antibody to IFN-gamma prevented any increase in C2 synthesis in monocyte cultures containing lymphocytes or LCM, C2 SpFA was still increased. Thus a second lymphocyte product is responsible for this 'oxidation' effect. This production of 'oxidized' C2 by monocytes and further 'oxidation' by the action of either lymphocytes or gamma-interferon might play a significant role in the perpetuation of complement activation at sites of inflammation.

Cells, Cultured↗
PubMed1989

Control of immune complexes by the classical pathway.

The association between inherited deficiencies of the classical pathway complement components (C1q, C1r, C1s, C4, C2 and C3) and immune complex disease shows that complement is involved in protection against the development of immune complex disease (ICD). This protection is conferred by the ability of the complement system to keep antigen antibody complexes (IC) small and soluble. Two mechanisms exist, prevention of immune precipitation (PIP), which inhibits the formation of large insoluble lattices when IC are formed in the presence of complement (nascent IC), and solubilisation of preformed immune precipitates (SOL). PIP is probably the more important as it is unlikely that, in vivo, IC are ever formed in the absence of complement. PIP displays an absolute dependency upon the classical pathway while SOL is alternative pathway dependent. However, for optimal efficiency SOL requires an intact classical pathway. Thus the classical pathway plays a role in both PIP and SOL. The end result of both processes is the covalent binding of C3b to the IC lattice, which not only keeps IC soluble, but permits binding to CR1 for removal from the circulation. The sera of patients with ICD contain a factor (s) which inhibits PIP. The sera of RA patients inhibits PIP and purified IgM-RF has been shown to inhibit this function. However a second inhibitor of PIP has recently been purified, a glycoprotein (Mr 60 kd) (gp60) which is present in normal serum and in increased concentration in RA sera. Gp60 binds to the Fc piece of IgG, but not to IgA or IgM, and competes with C1q for a binding site on IgG Fc. Thus gp60 appears to act by preventing binding and activation of C1 by IgG containing IC.

Antigen-Antibody Complex↗
PubMed1989

Familial properdin deficiency associated with chronic discoid lupus erythematosus.

A large family comprised of 18 members is described. Four male members are properdin-deficient, all are healthy bar the index patient who presented with chronic discoid lupus erythematosus. Serum from properdin-deficient males had a reduced ability to lyse rabbit erythrocytes via the alternative pathway or solubilize pre-formed immune complexes. Addition of purified properdin restored these activities. Classical pathway activity was normal. Definite, probable and possible female carriers had normal classical and alternative pathway activities.

Family↗