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L V Kozlov

Publications and source records attributed to L V Kozlov.

At least 19 recordsLinked to original sources
PubMed2004

[Immunological features of rheumatoid arthritis in patients infected with viruses of hepatitis B, C and in patients with cryoglobulinemia].

AIM: To specify immunological features of rheumatoid arthritis (RA) associated with hepatitis B, C viruses (HBV, HCV) and cryoglobulinemia (CGE). MATERIAL AND METHODS: Four groups of patients with verified RA were examined immunologically: infected with HCV, infected with HBV, with CGE diagnosed by the capillary method, free of HBV, HCV, CGE. CGE was estimated by the spectrophotometric method, functional activity of the complement components--by hemolytic micromethod. Polymerase chain reaction, identification of serological markers of viral hepatitides B and C were conducted with application of commercial kits produced in Russia. RESULTS: In RA patients infected with HBV and HCV, functional activity of the complement was significantly reduced. RA patients with hepatitis C and CGE showed hypoactivity of all the complement components. A classic course of RA was associated with elevated levels of C1 and C3 components in normal values of C1q, C2, C4 and C5 components. CGE was highest in RA+HCV and RA+CGE groups. CONCLUSION: The study of immunological features of RA associated with HCV, HBV and CGE is important not only in scientific but also in practical aspect as it indicates the necessity of treating the above conditions with drugs which do not suppress complement system significantly.

Adolescent↗
PubMed2001

Action of nonviral gene delivery vectors on human complement system: low anticomplementary activity of lipoplexes based on lacZ plasmid and phospholipid/oligocation liposomes.

A simple test-system has been developed for the first time in order to detect the ability of effectors (lipoplexes) to activate the complement system in an antibody-independent manner to serve as acceptors of nascent C4b and to inhibit formation of the key enzyme of complement, C3-convertase. The effect of plasmid DNA (pCMV-SPORT-LacZ), negatively charged cardiolipin (CL), neutral phosphatidylcholine (PC) vesicles and their lipoplexes, on the complement system was studied using the method developed. It was revealed that PC vesicles did not affect the complement system, while CL vesicles manifested low activation. The influence of plasmid DNA and its lipoplex based on PC liposomes as well on the complement system was very low. PC/LacZ lipoplex (143 microg/ml) acted on the complement system like 5.36 microg/ml heat aggregated IgG (agg) (the level of no pathological ruptures), whereas CL/LacZ lipoplex (143 microg/ml) acted similar to 10.7 microg/ml IgG (agg). Thus, weak activation of the complement system with CL lipoplex, and even weaker for the PC lipoplex testified to the use of neutral and positively charged lipoplexes preferably in gene therapy protocols. The technique can also be used for testing the influence of injectable gene therapy vectors on the complement system.

Animals↗
PubMed2000

[Isotyping of human C4 complement using differences in the functional activity of C4A and C4B isotypes].

The difference in the functional activity of the isotypes A and B of component C4 of human complement was used to determine their ratio and to detect the inherited deficiency of the isotypes. ELISA methods were developed for the quantitative assay of component C4 (conventional sandwich method) and its functional activity. When determining the functional activity, the classic pathway of the complement and therefore of component C4 was activated by activators sorbed on ELISA microplates (immunoglobulin IgG3 or liposaccharide of the Shigella sonnei cell walls, which activates the complement by binding component C1). The nascent fragment C4b is covalently bound to the target activator; C4Ab binds better to the target protein (immunoglobulin), and C4Bb to the target carbohydrate (liposaccharide). Therefore, when immunoglobulin is a target activator, isotype C4A is bound and determined; and when the complement is activated by liposaccharide, isotype C4B is determined. The ratio of the activities determined by the two methods indicates a deficiency in the individual isotypes of component C4 or its absence. The rabbit polyclonal monospecific antibodies against the human component C4 and the conjugates of these antibodies with horseradish peroxidase were used in the methods described.

Animals↗
PubMed2000

Cellular localization of the galactose-binding lectin from human serum.

An SL2 lectin was isolated from human serum and characterized previously; cellular localization of the lectin was studied using polyclonal rabbit antibodies. According to cytofluorimetry, anti-SL2 antibodies bound only to lymphocytes and monocytes but not to other blood cells. Antibodies bound to Jurkat T cell lymphoma but did not interact with IM-9 cells of B cell origin. Moreover, the Jurkat cells bound oligosaccharides having the highest affinity to SL2 (GalNAcalpha_and Fucalpha1-2Gal), and this interaction was inhibited by anti-SL2 antibodies. Lysis of the Jurkat cells with subsequent electrophoresis and Western blotting indicates that anti-SL2 antibodies recognized a 14-kD protein.

Animals↗
PubMed2000

[Inhibition of binding of activated compliment component C4b with its target].

The inhibition of covalent binding of the nascent C4b fragment of the human complement component to its natural target, immunoglobulin G, was studied. To this end, an immunoenzyme system was developed. In this ELISA method, the complement was activated on the sorbed IgG molecules and the resulting nascent C4b fragment acylated IgG or interacted with a competitive inhibitor added to the system. The inhibition constants for binding of the nascent C4b to its target were determined for immunoglobulins G1, G2, G3, G4, M, and A1, as well as for ferritin, yeast mannan, capsid polysaccharides of the Neisseria meningitidis A, B, and C serotypes, diphtheria anatoxin, epinephrine, and salicylic acid. On the basis of the experimental data, the immunoglobulin role at the activation stage of the complement regulation cascade, the relationship between the antigen immunogenicity and its ability to interact with C4b, and the direct effect of a number of therapeutic agents on the complement system were discussed. Lectins of various specificities were shown to inhibit the enzymic activation of C4 by the first complement component and the subsequent C4b sorption to its target, which allowed us to suggest that some oligosaccharide fragments of the C1s and C4 molecules are spatially close to the C1s active site and to the thioester bond of C4.

Complement Activation↗
PubMed1998

[Inhibition of formation of complement C5-convertase].

Control of the formation of complement C5-convertase is an important factor in maintaining human homeostasis. Some physiologically active endogenous and exogenous substances were shown to be capable of exerting such control. A method was developed for studying the influence of the effectors on the formation of classical-complement-pathway C5-convertase from C3-convertase stabilized by nickel ions. Immunoglobulins G and M, recombinant alpha and gamma interferons, serotonin, epinephrine, histamine, and ethanol were studied as effectors. The binding constants of the effectors with C3b, the active C3 component, and the values of the maximal effect were determined to evaluate the physiological importance of the effectors. The inhibition of C5-convertase generation was observed in all cases except for IgG and IgM (rheumatoid factor), which showed no effect and activating effect, respectively.

Adjuvants, Immunologic↗
PubMed1998

[Activation of kallikrein-kinin system, degranulating activity of neutrophils and blood-brain barrier in schizophrenia].

To evaluate permeability of blood-brain barrier (BBB) some immunological and biochemical indices were used. The levels of the activity of serum kallikrein-kinin system (KKS), compliment system, C-reactive protein (CRP) concentration, blood inhibitory potential, metabolic and degranulating activities of neutrophils, as well as functional activity of leukocytic elastase were investigated in 30 patients. Acute schizophrenic attack was accompanied by both activation of KKS and by the increase of functional activity of alfa-1-proteinase inhibitor. The increase of CRP levels, high hemolytic activity of complement as well as considerable degranulating activity of polymorphonuclear leukocytes may be the causes of the damage of BBB permeability during acute schizophrenic attack.

Acute Disease↗
PubMed1997

[Enzyme linked immunosorbent assay for characterization of affinity and epitope specificity of antibodies to a polysaccharide antigen].

The use of the Langmuir equation for processing ELISA data (the sandwich variant) helped to ascribe a physical sense to the parameters of the optimization of the antigen-antibody titration curve: the maximum response that characterizes complete binding corresponds to the saturation of all epitopes of the antigen, and the concentration at which half of the maximum response is attained corresponds to the dissociation constant of the immune complex, i.e., to the average affinity of the antibodies. The algorithm was tested for systems in which antibodies against IgE and IgD were sorbed on a support, and the antigen bound was determined by the antibodies conjugated with peroxidase. A good fit of the experimental and theoretical curves and reasonable values for the affinity constants were found. In another system, the binding of specific IgG, IgM, and IgA antibodies with the polysaccharide from Neisseria meningitidis serotype A was studied during vaccine testing. The structural simplicity of the antigen molecule made it possible to suggest the presence of two main epitopes and to reveal the dynamics of formation of the antibodies to them.

Adolescent↗
PubMed1994

[Features of complement proteinase function].

Classical and alternative pathways of complement are considered which are stringently controlled cascades of proteolytic reactions. Peculiarities of working of various components of complement are characterized, ways are described of the regulation and inhibition of the system realized in the nature to achieve the highest reliability necessary for homeostasis.

Amino Acid Sequence↗
PubMed1991

Inorganic supports coated with N-substituted polyacrylamides: application to biospecific chromatography of proteins.

Wide porous glass (WPG) chemically coated with a poly-N-(2-hydroxyethyl)acrylamide layer is proposed as a carrier of biospecific ligands in affinity chromatography. The method of WPG chemical modification includes synthesis of the gamma-aminopropyl derivative followed by chemical adsorption of poly(p-nitrophenyl acrylate). Ester groups of the polyacrylate-coated WPG can be used for coupling the ligands bearing primary amino groups. Condensation of esters with ethanolamine yields a poly-N-(2-hydroxyethyl)acrylamide-coated support with non-specific adsorption properties resembling those of Sepharose 4B. Human IgG immobilized on the polyacrylate support was used for isolation of the first complement component from human serum and for its separation into subcomponents C1r, C1s and C1q by a one-step method. An unbound part of serum may be used as the R1 reagent for determining haemolytic C1 activity. The stepwise elution of C1r, C1s and C1q from the column reflects the course of C1 breakdown after its activation on immune complex formation.

Acrylic Resins↗
PubMed1991

[Insulin-dependent complement activity in the serum of patients with diabetes mellitus].

Complement system was comparatively evaluated in 68 patients with diabetes mellitus and 104 healthy subjects. Hemolytic activity was examined for components C1, C2, C3, C4 and C5, and overall activity of the classic pathways was defined. The complement status appeared different for men and women. Females demonstrated hypofunction of the majority of the complement components, subcompensation in the absence of angiopathies, in decompensation complicated by angiopathies the activity was enhanced. In uneventful course of diabetes mellitus in males component C4 was activated remaining above normal though reduced in decompensation with angiopathies. High complement level in females could serve an aggravating factor, it depends on the dose of exogenic insulin.

Adolescent↗
PubMed1989

[Stepwise dissociation of subcomponents of C1, the first component of human complement, upon activation on an affinity sorbent].

An affinity sorbent comprising macroporous glass coated with the polymer with the polymer with immobilized immunoglobulin IgG was used for the isolation from human serum of the first component of the complement and for its separation into subcomponents C1r, C1s and C1q by the one-step procedure. Serum C1 was quantitatively bound to the sorbent at 0 degrees C. The unbound part of the serum can be used as a R1 reagent for determining the hemolytic activity of C1. After activation of bound C1 by heating (30 degrees C, 40 min) the activated subcomponent C1r is eluted from the sorbent. Stepwise elution with EDTA at pH 7.4 or with EDTA + 1 M NaCl at pH 8.5 results in a selective and quantitative elution of the activated subcomponent C1s and subcomponent C1q. Stepwise elution of C1 subcomponents from the affinity sorbent after activation reflects the process of C1 breakdown following its activation on immune complexes.

Animals↗
PubMed1989

[Major complement inhibiting factors from the venom of the Central Asian cobra Naja naja oxiana].

The properties of two anticomplementic factors isolated by CM-Sepharose chromatography from the basic non-adsorbed on DEAE-Sepharose fraction of the Central Asian cobra Naja naja oxiana venom, were studied. Of these three factors (CFB-I, CFB-II and CFB-III) the latter had been characterized earlier. CFB-I was shown to be a protein with an N-terminal Asp and a molecular mass of about 39 kDa (data from gel chromatography); its content in the venom is 3.6 mg/g of dry venom. The protein inhibits mainly the classical pathway of the complement activation, being bound to component C4 (Ki = 9 nM). CFB-I seems to be analogous to the CI inhibitor from the venom of the Naja haje cobra. An analysis of the N-terminal sequence of CFB-II showed it to be identical to the earlier characterized cytotoxin I. CFB-I inhibits the formation of C3 convertase with Ki = 2.2-2.8 microM by way of binding to C4b and thus interfering with the component C2 sorption.

Animals↗
PubMed1989

[Complement-inhibiting acidic factors from the venom of Central Asian cobra Naja naja oxiana].

Two anticomplementic factors isolated from the venom of the Central Asian cobra Naja naja oxiana by chromatography on DEAE-Sepharose CL-6B and subsequent gel filtration on Sephacryl S-200 were studied. Of these, five factors (CFA-Ia, CFA-Ib, CFA-Ic, CFA-IIa and CFA-IIb), CFA-Ib had been characterized earlier, while CFA-Ia was assigned to a previously identified H-CoF factor. It was shown that CFA-Ic has a molecular mass of 3900 Da; its content in the venom amounts to 2.6 mg/g of dry venom. This factor inhibits the classical pathway of C3 convertase formation abrogating the C2 component activation by subcomponent C1s [Ki = (2.5 +/- 0.8).10(-7) M]. CFA-IIa and CFA-IIb are present in the venom in very low amounts (2 mg/g) and have Mr of 5700 and 3200 Da, respectively. The complement-inhibiting action was studied for a more active CFA-IIa. Factor CFA-IIa was shown to inactivate the native component of C2 with a rate constant, k, of (2.7 +/- 0.2).10(3) s-1M-1 (37 degrees C, pH 7.4). CFA-IIa had no effect on C2 and C2a within their complexes with C4b.

Chromatography, DEAE-Cellulose↗
PubMed1987

[Formation of classical C3 convertase during the alternative pathway of human complement activation].

The fluid phase C3 convertase of the alternative pathway of human complement activation has been constructed from the isolated C3 component and from purified factors B and D. The enzyme was able to activate the isolated components C4 and C2 in the presence of C4 but had no effect on C2 in the absence of C4. The C4 and C2 activation was monitored by the loss of their hemolytic activity during the incubation with the alternative fluid phase C3 convertase. The activation of C4 and C2 components by the membrane-bound alternative C3 convertase formed on red cells (EC3bBb) was followed by the formation of C3 convertase of the classic pathway--EC4b2a. This resulted in the enhancement of hemolysis.

Animals↗
PubMed1986

[Inhibition of the binding and activation of the first component of human complement. The effect of synthetic peptides, immunoglobulin fragments and various proteins].

A study has been carried out on the inhibition of the subcomponent Clq binding to sensitized sheep erythrocytes (EA) by the following synthetic peptides mimicking the structure of a putative complement binding site of immunoglobulin G: Boc-Trp-Tyr, Boc-Tyr-Trp, Trp-Tyr, Boc-Trp-Phe, Boc-D-Trp-D-Tyr, Boc-D-Tyr-D-Trp, Boc-Leu-Leu, Ac-Phe-Tyr, and commercial Thr-Lys-Pro-Arg (tuftsin). Boc-Trp-Tyr was found to be the most potent inhibitor of Clq binding to EA (Ki 2.86 X 10(-4) M), tuftsin ranking second with Ki 6 X 10(-4) M. The D,D-dipeptides failed to inhibit the Clq binding at the investigated concentrations. Insoluble Z-Trp-Tyr-OMe activated a classical pathway of complement system, as monitored by consumption of C4, C2 and C3 components. Synthetic octapeptide Boc-Glu-Val-Asp-Leu-Leu-Lys-Asp-Glu-OMe (corresponding to the sequence 36-43 of beta 2-microglobulin) inhibited the Clq binding with Ki 4.7 X 10(-4) M, which gave grounds for localizing the complement binding site in beta 2-microglobulin. The finding in the Clq structure of the peptide sequence homologous to than of the pepsin active site, as well as the close similarity in the specificity of these proteins towards hydrophobic amino acid residues justified the assumption on the same structural bases of their specificity. The results of the present study, along with the literature data, underlie the hypothesis on the involvement in the complement binding of the following IgG residues: Trp277, Tyr278, Lys320, Lys322, Glu318 and Lys290. The enlisted residues are closely located in the three-dimensional structure of the CH2 domain of IgG. Lysozyme and lactalbumin having the sequences homologous to Trp277-Tyr278 of IgG inhibited Clq binding to EA with Ki 3 and 1.5 microM respectively.

Amino Acid Sequence↗
PubMed1985

[Binding of activated C3b component with complement effector].

Various nucleophilic agents (acceptors) react with thiolester group of nascent activated fragment (C3b) of the third complement component. The C3b-acceptors binding prevents transformation of C3 convertase to C5 convertase and results in inhibition of the cell-target lysis. A convenient method of monitoring the EAC142 to EAC1423 transformation was elaborated. Character of the inhibition suggests that the covalent binding follows a stage of the reversible C3b-acceptor complex formation. The method allows to determine the maximum of inhibition of the C5 convertase formation and the dissociation constant of the reversible C3b-acceptor complex, which reflects the C3b affinity to this acceptor.

Animals↗