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M R Daha

Publications and source records attributed to M R Daha.

At least 361 records · Page 20Linked to original sources
PubMed1987

Activation of the alternative pathway of complement by human serum IgA.

In order to study the activation of complement by soluble aggregates of human polyclonal serum IgA, lysis of sheep erythrocytes (E) coated with several IgA preparations was used as a model. A complement nonactivating monoclonal mouse IgG1 against IgA was used to coat the cells. IgA, isolated from normal human serum, was aggregated by either N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP), glutaraldehyde, carbodiimide or heating. Depending on the size of the aggregates, and on the method of aggregation, E coated with aggregated IgA (E gamma 1.AIgA) could be lysed. The alternative pathway of complement appeared to mediate the lysis because the latter was observed in the presence of EGTA containing 5 mM Mg2+ (MgEGTA) and properdin (P) was deposited on the cells. Furthermore, no lysis was observed in C3-deficient serum. In the absence of AIgA the cells were not lysed, and no P deposition was observed. In another set of experiments E gamma 1.AIgA were first reacted with purified C3, B, D and P for 30 min at 30 degrees C, and subsequently in rat serum EDTA at 37 degrees C. Lysis occurred when E gamma 1.AIgA were prepared using SPDP-, glutaraldehyde- or carbodiimide-AIgA. Incubation of 100 micrograms/ml SPDP-AIgA with normal human serum for 30 min at 37 degrees C in the presence or absence of MgEGTA also induced consumption of total complement. The other soluble AIgA preparations were less effective in activating complement. These results suggest that polymeric serum IgA is capable of activating the alternative pathway of complement.

Complement Activation↗
PubMed1987

Endothelial cell lysis induced by lymphokine-activated human peripheral blood mononuclear cells.

In vitro exposure of human peripheral blood mononuclear cells (PBMC) to interleukin 2 results in the generation of lymphokine-activated killer (LAK) cells. Such LAK cells exhibit cytotoxicity against a spectrum of tumor target cell lines whereas they apparently do not affect normal tissues. In this report we show that PBMC that have been activated with T cell growth factor lyse trypsinized human umbilical cord venous endothelial cells as well as endothelial cell monolayers in a dose-dependent manner. Microscopic analysis showed that during the 4-h incubation period cell clumps containing detached endothelial cells and LAK cells were formed. When these clumps were evaluated with trypan blue the endothelial cells stained positive whereas LAK cells excluded the dye. No lysis occurred when fresh PBMC were added to target endothelial cells. The endothelial cell kill could not be blocked with an anti-LFA-1 antibody nor with intact OKT3 or F(ab')2 fragments of WT32. We conclude that lymphokine-activated PBMC exhibit cell-mediated endothelial cell detachment and lysis.

Antibodies, Monoclonal↗
PubMed1987

Complement-mediated solubilization of rat IgA immune precipitates.

The complement-mediated solubilization (CMS) of immunoprecipitates (IP) consisting of DNP-rat serum albumin (RSA) and rat monoclonal anti-DNP antibodies of the IgA [both polymeric (p-) and monomeric (m-)] or IgG2b (sub)class was studied. In contrast to IgG2b IP, solubilization of IgA IP was only observed in an autologous system, with rat serum as the source of complement. IP prepared using m-IgA were solubilized faster than those prepared using p-IgA. Analysis of both affinity and avidity of the antibodies, indicated that this difference may be due to the lower avidity of the m-IgA antibodies as compared to p-IgA. Analysis of the solubilized IP revealed deposition of C3 and C4 on IgG2b, and only C3 on IgA IP. These results point toward a role of the alternative pathway in the solubilization of IgA IP. Size analysis of the solubilized IgA IP employing sucrose density gradient ultracentrifugation, indicated that these were heterogeneous, with a size generally larger than 19 S.

Animals↗
PubMed1987

Activation of complement by soluble IgG aggregates and their subsequent interaction with macrophages.

The mononuclear phagocyte system (MPS) plays an important role in the removal of both particulate and soluble immunogenic material from the circulation. E.IgG adhere to mononuclear phagocytes if the Fc portion of the IgG can interact with the phagocytes' Fc receptors. Simultaneous sensitization with IgG and C3b enhances the effectiveness of binding and ingestion. If soluble material cannot adhere to the surface of macrophages, it will be endocytosed in vitro via fluid-phase pinocytosis at the concentration that is present in the medium. If the material adheres to the cell's surface via its chemical properties or via specific receptors, it will be selectively concentrated at the cell's surface and endocytosed by an adsorptive pinocytosis. Ingestion of IC via Fc gamma R and C3b depends on the ability of the antibodies to interact with Fc gamma R and their capacity to activate the complement system. IC-bound C3b enhances the adsorptive pinocytosis of IC. Soluble AIgG are also pinocytosed more efficiently when C3b is bound to AIgG. The degree of endocytosis varies with the level of C3b sensitization. The highly effective C3b-mediated pinocytosis can be abolished by treating the macrophages with trypsin to inactivate C3bR. This observation illustrates that C3-mediated pinocytosis can replace Fc-mediated pinocytosis in unstimulated macrophages. Soluble IC and AIgG are removed from the circulation mainly by hepatic Kupffer cells. It seems that the size, the Ag/Ab ratio, the capacity of the IC to bind C1, activate C1, and allow deposition of C3b together with the degree of phagocyte activation determine the degree of binding and subsequent degradation of soluble IC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Association of rheumatoid factors in renal transplant recipients with cytomegalovirus infection and not with rejection.

Because rheumatoid factors (RF) were detected in the circulation of the majority of early renal transplant recipients and could be eluted from rejected transplants, RF were hypothesized to be related to antibody responses to the histoincompatible graft. The possibility that RF production might have been related to infection and not rejection has not been considered previously. Therefore, we investigated serial serum samples from 147 adult renal transplant recipients for RF with latex agglutination and radioimmune assays. RF were detected in the sera of 32 patients, 30 of whom had coincident active cytomegalovirus (CMV) infections. Another 45 patients with active CMV infections did not have detectable circulating RF. In contrast, of 74 patients who experienced a total of 103 treated reversible or irreversible rejection episodes in the absence of evidence of active CMV infections, only 2 patients produced RF during their rejection episodes. Nine of the patients who did not produce RF during a rejection episode subsequently produced RF during a later CMV infection. These data indicate that RF production in renal transplant recipients is associated with CMV infection and not rejection. Moreover, RF production was found to be more frequently associated with primary and severe CMV infections than with secondary or milder CMV infections. RF production was not more frequent in patients who were HLA-DR-4-positive., older, or female, characteristics that have been associated with RF production in other populations. All of the sera with detectable RF contained IgM antibodies that were directed to the Fc portion of human IgG, and about half contained additional IgM antibodies directed to Fab. Thus CMV infections may be the stimuli for the IgM anti-Fab antibodies that have been reported in pretransplant serum samples. Eleven patients produced IgG or IgA RF in addition to IgM RF during CMV infections.

Adult↗
PubMed1987

Perivascular deposits of IgM in the skin of transplant recipients during active cytomegalovirus infections. Correlation with IgM rheumatoid factors and IgM immune complexes.

Skin biopsies from 30 renal transplant patients were investigated for cellular infiltrates and deposits of IgM, IgA, IgG, C3, and C5-9 neoantigen. Granular perivascular deposits of IgM were detected in biopsies of 8 of 14 patients during active cytomegalovirus (CMV) infections and in none of 16 controls. In 5 biopsies, the IgM deposits were accompanied by little or no IgG, IgA, or C, while in 3 biopsies definite C3 deposits were present. One of the biopsies with C3 deposits also had C5-9 deposits and another had C5-9 and IgA deposits. Three monoclonal antibodies failed to detect early or late nuclear antigens of CMV in the deposits. These deposits were not associated with clinically evident manifestations of vasculitis. A strong correlation was found between IgM deposits in the skin and IgM circulating immune complexes (CIC) and also IgM rheumatoid factor (RF). The deposition of IgM was not more frequent in primary than in secondary CMV infections, and it did not correlate with the production of IgM antibodies that were specific for CMV antigens.

Antigen-Antibody Complex↗
PubMed1987

The IgA-binding lectin jacalin induces complement activation by inhibition of C-1-inactivator function.

Jacalin, a D-galactose-specific lectin from jackfruit, interacts with human IgA and one or two other serum proteins. Incubation of jacalin with fresh human serum was shown to result in activation of the complement system. Therefore the mechanism of complement activation by jacalin was studied. Jacalin was extracted from jackfruit seeds (crude preparation) and purified to homogeneity by affinity chromatography on IgA-Sepharose to yield a pure preparation of jacalin. Both crude and pure jacalin were able to activate complement, accompanied by conversion of C3. Consumption of C1, C4 and C-1-inactivator (C-1-In) indicated involvement of the classical pathway. Aggregated IgG (AIgG) caused partial (38%) and jacalin induced complete consumption of C1-In functional activity. It was found upon Ouchterlony analysis that jacalin forms a precipitation line with purified C-1-In. In addition binding of 125I-C-1-In to jacalin-Sepharose was observed, and this binding was inhibitable by either secretory IgA or D-galactose. Next to binding of jacalin to C-1-In, jacalin was also shown to inhibit the functional activity of C-1-In. These results indicate that jacalin induces complement activation by inhibition of C-1-In function and thereby facilitates the activation of precursor C1 in either the absence or presence of low amounts of C1 activators.

Complement C1 Inactivator Proteins↗
PubMed1987

Inhibition of T cell cytolytic potential by concanavalin A: a result of activation?

We investigated the effects of concanavalin A (Con A) on T cell-mediated lympholysis. Human cytotoxic T cell lines were generated from peripheral blood and these lines were shown to lyse lectin-coated K562 target cells. Addition of soluble Con A to the assay resulted in a dose-dependent inhibition of the cytolysis. Preincubation experiments demonstrated that this inhibitory effect was exerted at the effector cell level. F(ab')2 fragments of WT32, a monoclonal antibody against T3, blocked the cytolysis of Con A-preincubated K562 target cells to a large extent. We further showed that Con A strongly inhibited the cytolysis exerted by alloantigen-specific, major histocompatibility complex (MHC)-restricted cytotoxic T cell lines against their specific targets. On the other hand, Con A had no clear inhibitory effect on the cytotoxicity of freshly isolated peripheral blood mononuclear cells against K562 target cells. We hypothesize that Con A-induced inhibition of cytotoxicity may be explained by a direct triggering of the lytic potential of activated T cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Immunopathological abnormalities in the normal skin of patients with rheumatoid arthritis in relation to clinical and serological findings: a one year follow up study.

Fifty two patients with seropositive rheumatoid arthritis (RA) were studied over a period of one year to investigate possible relationships among changes of circulating immune complexes (CIC), deposits of immunoglobulins and complement around the cutaneous blood vessels, clinical activity of the disease, and the presence of extra-articular manifestations (EAM). The presence or absence of IgM and C3 in and around the cutaneous blood vessels correlated significantly with the presence or absence of extra-articular features in cross sectional and longitudinal studies. Patients with evidence of these cutaneous immune deposits also had a greater prevalence of CIC as determined by the Clq binding assay (ClqBA) or polyethylene glycol (PEG) assay for IC containing IgM (IgM IC). Although the degree of perivascular mononuclear cell infiltration around the blood vessels in the papillary dermis was related to the patients' clinical state at the initial assessment, it did not correlate with the later changes in the activity of the joint disease or the occurrence of EAM. Thus the deposition of immunoglobulin or complement, or both, seems to be independent of cellular infiltration. The meaning of these cellular infiltrates is not yet fully understood. Our study has shown that many patients with RA who appeared to have only joint disease in fact had subclinical systemic disease as reflected by a positive skin biopsy or CIC. Moreover, the disappearance of IgM deposits from the skin correlated with the disappearance of EAM and improvement of joint disease.

Adolescent↗
PubMed1987

Mononuclear phagocyte system Fc-receptor function in patients with seropositive rheumatoid arthritis.

Mononuclear phagocyte system (MPS) Fc-receptor function in 20 patients with seropositive rheumatoid arthritis (RA) was investigated using radiolabelled autologous erythrocytes coated with an average of 5,800 molecules of anti-rhesus IgG (E. IgG). Although clearance times (T1/2) of E. IgG tended to be longer in RA patients than those in healthy controls (46 +/- 6 min vs 38 +/- 5 min, mean +/- s.e.m., P = 0.38), this did not reach statistical significance. Liver spleen uptake ratios (LS ratios) were increased in patients with RA (13/100 +/- 1/100 vs 7/100 +/- 1/100, P less than 0.05). There was no correlation of T1/2 or LS ratios with articular disease activity, vasculitis, ESR, IgM containing immune complex levels or Clq-binding immune complex levels. Although Clq-binding immune complex levels were significantly higher in patients with vasculitis than in those without (P less than 0.01), T1/2 and LS ratios did not differ in these two groups of patients. The T1/2 and LS ratios of E.IgG did not reveal a defect in MPS Fc-receptor function and did not correlate with one of the above-mentioned clinical and immunological parameters. We suggest that in order to establish a possible defect in Fc-receptor function correlating with disease activity and immune complex levels in RA patients, soluble immune complexes or immune complex-like material should be used as probes.

Adult↗
PubMed1987

IgA- and secretory IgA-opsonized S. aureus induce a respiratory burst and phagocytosis by polymorphonuclear leucocytes.

The aim of the present study was to investigate whether corpuscular immune complexes containing human IgA were able to interact with human polymorphonuclear leucocytes (PMN). As a model for corpuscular IgA immune complexes (IgA IC), heat-killed Staphylococcus aureus (S. aureus) opsonized with either purified human serum IgA or purified secretory IgA (sIgA) isolated from human colostrum was used. In order to determine the capacity of IgA and sIgA to opsonize S. aureus the phagocytosis of these IgA IC by PMN was measured. S. aureus opsonized with IgA, sIgA, IgG, heat-inactivated serum or fresh serum was ingested by 23 +/- 8%; 28 +/- 9%; 39 +/- 7%; 31 +/- 10% and 78 +/- 10% of the PMN (S. aureus:PMN = 10:1, n = 4), respectively. These results were significantly different (P less than 0.05) from the percentage obtained with unopsonized S. aureus (9 +/- 3%), indicating that IgA and sIgA induce ingestion of S. aureus. The phagocytic index for PMN incubated with S. aureus opsonized with sIgA (231) was higher than for S. aureus opsonized with IgA (119), indicating a better uptake of S. aureus opsonized with sIgA in our system. Bacteria opsonized with either IgA or sIgA were also capable of triggering H2O2 release of PMN in a dose-dependent manner. The H2O2 release by PMN triggered with S. aureus opsonized with IgA could not be inhibited with a F(ab')2 anti-Fe gamma receptor monoclonal antibody, whereas the H2O2 release triggered with S. aureus opsonized with IgG was fully inhibited. Soluble heat-aggregated IgA (AIgA) also induced H2O2 release of PMN, suggesting that the IgA itself is essential for the induction of a respiratory burst.

Antigen-Antibody Complex↗
PubMed1987

Biocompatibility of hemodialysis using cuprophane membranes.

In a controlled study of the influence of hemodialysis on hemodynamics, complement system, leucocyte- and thrombocyte concentration was studied in two groups of five non-uremic dogs each. During the initial 30 min of dialysis with the commonly used cuprophane membrane, a transient but significant decrease of the mean aortic pressure and cardiac output occurred while simultaneously heart rate and systemic vascular resistance decreased. Thrombocyte concentration decreased significantly during the initial 60 min of dialysis due to sequestration in the dialyzer. Transient leucopenia due to pulmonary leucostasis occurred without decrease of the arterial oxygen tension. The simultaneous occurrence and transient character of the hemodynamic changes, leucopenia and thrombocytopenia suggest a relationship between these phenomena. These results indicate that the biocompatibility of cuprophane dialysis membranes is of importance not only with regard to changes in the leucocyte- and thrombocyte-count but also with regard to hemodynamic changes.

Animals↗
PubMed1987

Membrane attack complex of complement in leukocytoclastic vasculitis of the skin. Presence and possible pathogenetic role.

The presence of the membrane attack complex of complement (MAC) was studied by a two-step immunofluorescence method in 15 patients with leukocytoclastic vasculitis of the skin, using an antibody against MAC neoantigen. Perivascular deposits of MAC were present in 13 specimens of lesional skin and only two specimens of clinically uninvolved skin, suggesting a possible pathogenetic role for MAC in the development of a skin lesion. Control studies were performed on the clinically normal skin of 15 individuals (11 patients with various nonbullous skin diseases and four healthy volunteers) and on skin lesions of seven patients with inflammatory skin diseases. In the clinically normal skin of only one patient, perivascular deposits of MAC were detected. This patient had rheumatoid arthritis and a cutaneous eruption due to the administration of aurothioglucose. We conclude that the activation of the terminal components of the complement system may play an important role in the formation of lesions in leukocytoclastic vasculitis of the skin, but is not an indispensable condition.

Adult↗