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Biomedical subjects

M D Kazatchkine

Publications and source records attributed to M D Kazatchkine.

At least 19 recordsLinked to original sources
PubMed1999

Efficacy of a five-drug combination including ritonavir, saquinavir and efavirenz in patients who failed on a conventional triple-drug regimen: phenotypic resistance to protease inhibitors predicts outcome of therapy.

OBJECTIVE: to assess the safety and efficacy of a combination of ritonavir, efavirenz and two recycled nucleosides in patients who failed on a conventional triple-drug regimen including indinavir or ritonavir. METHODS: An open label study of ritonavir (100 mg twice daily), saquinavir (1000 mg twice daily), efavirenz (600 mg per day) and nucleoside analogues in 32 saquinavir- and efavirenz-naive protease inhibitor-experienced patients. Patients were included on the basis of plasma levels of HIV RNA above 5000 copies/ml while on conventional antiretroviral therapy. Phenotypic resistance and genotypic resistance mutations to saquinavir were assessed at baseline. Peak and trough plasma levels of saquinavir were monitored throughout the study. RESULTS: Median CD4 cell counts and median plasma HIV RNA at baseline were 258 x 10(6)/l and 4.31 log10 copies/ml, respectively. The plasma viral load decreased by a median of 1.20 log10 copies/ml and the CD4 cell count increased by a median 60 x 10(6) cells/l at week 24 of therapy. Seventy-one per cent of the patients achieved a plasma viral load < 500 copies/ml and 45% achieved a viral load < 50 copies/ml. Patients exhibiting phenotypic resistance to saquinavir at baseline experienced a median decrease in HIV RNA of 0.91 log10 copies/ml at week 24 of therapy, as compared with a decrease of 1.52 log10 copies/ml in those exhibiting sensitive viral strains (P = 0.03). Genotypic resistance to saquinavir was not predictive of virologic failure. CONCLUSION: Our results indicate that the combination of ritonavir, saquinavir and efavirenz is safe and effective at 24 weeks in over two-thirds of patients who previously failed on highly active antiretroviral therapy, and that the determination of phenotypic resistance may be of greater value than the detection of resistance mutations to predict the outcome of salvage therapy in this setting.

Adult↗
PubMed1999

Compartmentalization of the IgG immune response to HIV-1 in breast milk.

OBJECTIVE: To evaluate the IgG immune response to HIV-1 in colostrum. METHODS: Paired serum and colostrum were collected from 16 asymptomatic HIV-1-infected women. IgG to gp160 and to four peptides (gp41 immunodominant DI domain, gp41/Id; EDLKWA epitope of DIII domain, gp41/K; gp120 C-terminus, gp120/Ct; V3 loop, gp120/V3) were evaluated in all samples. Functional activity of purified IgG was assessed for the ability to block transcytosis of cell-associated HIV-1 through a tight monolayer of endometrial epithelial cell line HEC1. RESULTS: IgG antibody to gp160 and to the four env-encoded synthetic peptides were detected in all specimens. The mean specific activity of IgG to gp41/K was 4.2 fold higher in colostrum than in paired serum. In contrast, mean specific activities of IgG to gp160 and gp41/Id were twofold higher in serum than in paired colostrum. Mean specific activities of IgG to gp120/V3 and to gp120/Ct were similar in systemic and milk compartments. Functional activity of IgG was evaluated in six paired serum and colostrum: in two women, serum IgG was 3.0 and 7.6 fold more efficient in blocking transcytosis than colostrum IgG; in one patient, colostrum IgG exhibited a 28 fold higher inhibitory capacity than serum IgG; in the remaining patients, serum and colostrum IgG demonstrated similar inhibitory activities against transcytosis of HIV. CONCLUSION: These features are consistent with a compartmentalization of the humoral IgG immune response to HIV within the mammary gland. Some HIV-1 antigens are able to induce a strong humoral mucosal immune response which may be of relevance for the design of a mucosal vaccine against HIV-1.

Adolescent↗
PubMed1999

Normal human serum contains natural antibodies reactive with autologous ABO blood group antigens.

It is widely accepted that the serum of healthy individuals contains natural antibodies only against those blood group A or B antigens that are not expressed on the individual's red blood cells. The mechanisms involved in tolerance to autologous blood group antigens remain unclear. In the present study, we show that IgM and IgG antibodies reactive with autologous blood group antigens are present in the immunoglobulin fraction of normal human serum. Natural IgG anti-A antibodies purified by affinity chromatography from IgG of individuals of blood group A exhibited an affinity for A trisaccharide antigen in the micromolar range and agglutinated A red cells at sixfold higher concentrations than those required for agglutination with affinity-purified anti-A IgG of individuals of blood group B. Whereas autoantibodies reactive with self A and B antigens are readily detected in purified IgG and IgM fractions, their expression is restricted in whole serum as a result of complementary interactions between variable regions of antibodies. These observations suggest that tolerance to autologous ABO blood group antigens is dependent on peripheral control of antibody autoreactivity.

ABO Blood-Group System↗
PubMed1999

Inhibition of cell adhesion by antibodies to Arg-Gly-Asp (RGD) in normal immunoglobulin for therapeutic use (intravenous immunoglobulin, IVIg).

Intravenous immunoglobulin (IVIg) therapy is associated with a broad range of immunomodulatory activities. Several of the postulated mechanisms of IVIg action relate to the presence of antibodies to molecules relevant for regulation of the immune response. This article reports that IVIg contains antibodies to the Arg-Gly-Asp (RGD) sequence, and the attachment site of a number of adhesive extracellular matrix proteins, including ligands for beta1, beta3, and beta5 integrins. Anti-RGD antibodies were identified in IVIg by enzyme-linked immunosorbent assay and by using the BIAcore (BIAcore, Uppsala, Sweden) technology. The affinity of anti-RGD antibodies to a synthetic RGD-containing peptide and to fibronectin (Fn) was found to be in the micromolar range. F(ab')2 fragments specific for RGD were purified from IVIg by affinity chromatography. Anti-RGD F(ab')2 antibodies inhibited adenosine diphosphate induced alphaIIb/beta3 integrin-mediated platelet aggregation and the adhesion of activated alpha4beta1 integrin-expressing B cells to Fn. Adhesion of unstimulated platelets to fibrinogen (Fg) involving both the gamma-chain dodecapeptide sequence and the RGD sequence was inhibited by anti-RGD antibodies. In addition, adhesion of thrombin-stimulated platelets to von Willebrand factor or Fg was completely inhibited by affinity-purified anti-RGD antibodies. Our results suggest that the presence of natural IgG antibodies to the RGD motif may contribute to the immunomodulatory and anti-inflammatory effects of therapeutic preparations of normal IgG.

Antibodies↗
PubMed1999

Defective self-reactive antibody repertoire of serum IgM in patients with hyper-IgM syndrome.

We have analyzed the self-reactive repertoires of IgM and IgG Abs in the serum of 19 patients with hyper-IgM syndrome (HIM) by means of a quantitative immunoblotting technique that allows for a quantitative comparison of Ab repertoires in health and disease by multiparametric statistical analysis. Normal tissue extracts of liver, lung, stomach, and kidney were used as sources of self Ags. Extracts of Pseudomonas aeruginosa and Staphylococcus epidermidis were used as sources of nonself Ags. We demonstrate a significant bias in repertoires of reactivities of IgM of patients with HIM with self Ags. Ab repertoires of IgM toward nonself Ags did not differ, however, between patients and controls. No difference was found between IgM repertoires of untreated patients and those of patients receiving substitutive treatment with i.v. IgG. IgG in the serum of HIM patients lacked reactivity with self Ags, although it exhibited a pattern of reactivity with nonself Ags that was similar to that of IgG of healthy controls. The data demonstrate that functional CD40-CD40 ligand interactions are essential for the selection of natural self-reactive B cell repertoires.

Adolescent↗
PubMed1999

Normal human immunoglobulin suppresses experimental myasthenia gravis in SCID mice.

Serum IgM has been shown to participate in the control of IgG autoreactivity in healthy subjects. We have recently shown that an immunoglobulin preparation of pooled normal human IgM (IVIgM) contains anti-idiotypic antibodies against disease-associated IgG autoantibodies in autoimmune patients and protects rats from experimental autoimmunity. The aim of the present study was to asses the in vitro and in vivo immunomodulatory effects of IVIgM in comparison with IgG, in SCID mice reconstituted with thymic cells from a myasthenia gravis patient. Non-leaky SCID mice were injected i.p. with 60 x 10(6) thymic cells from a patient with myasthenia gravis and 1 day later boosted with 10(6) irradiated acetylcholine receptor (AchR)-expressing TE671 cells. On days 14, 21 and 28, mice were treated with IVIgM or with equimolar amounts of human serum albumin. The level of anti-AchR antibodies in the sera of three out of four IgM-treated animals was less than 1 nM. Further, there was a significant decrease in the loss of endplate AchR on the diaphragms of IgM-treated SCID mice. These findings indicate that pooled normal IgM exerts an immunoregulatory role in experimental myasthenia gravis, and suggests that IgM may be considered as an alternative approach in the therapy of autommune diseases.

Animals↗
PubMed1999

Functional properties of soluble CD21.

Soluble receptors may display immunoregulatory properties by blocking interactions between ligands and their membrane receptors or by triggering specific biologic responses through interaction with counter part membrane receptors. A natural soluble form of CD21 that is cleaved from lymphocyte membrane CD21 circulates in normal human serum. Soluble CD21 retains the capacity to bind iC3b and CD23, the known ligands of membrane CD21. In a similar fashion to IgE complexes, another ligand of CD23, the soluble CD21 was shown to efficiently trigger CD23-signalling pathways in human monocytes. By inducing release of proinflammatory cytokines and upregulating expression of molecules involved in antigen presentation, soluble CD21 modulates critical monocyte functions that may be relevant to allergic and inflammatory disorders.

Humans↗
PubMed1999

Stability of natural self-reactive antibody repertoires during aging.

We have used a quantitative immunoblotting technique to analyze the repertoires of self-reactive antibodies in serum samples obtained from the same five healthy adults over a 25-year interval. The average age of the donors was 43 years at the time of the first serum sample and 69 years at the time of the second serum sample. The antibody repertoires of IgM and IgG were found to be strikingly similar among individuals in both early and late samples. Densitometric profiles of self-reactivity of serum IgM and of purified serum IgG remained unchanged over the 25-year interval. The total reactivity of serum IgG decreased significantly over the 25-year period. The observed stability of the natural self-reactive IgM and IgG antibody repertoires with aging supports the view that autoreactive B cells in the normal immune system are positively selected for reactivity with a limited set of immunodominant self-antigens throughout life.

Adult↗
PubMed1999

Catalytic activity of antibodies against factor VIII in patients with hemophilia A.

Hemophilia A is an X chromosome-linked recessive disorder resulting in defective or deficient factor VIII (FVIII) molecules, which, in its severe form, is a life-threatening and crippling hemorrhagic disease. Infusion of homologous FVIII to patients with severe hemophilia A results, in 25% of patients, in the emergence of alloantibodies against FVIII (inhibitors)( ref. 1) that inhibit FVIII procoagulant activity by steric hindrance of the interaction of FVIII either with stabilizing molecules, with molecules essential for its activity or with activating molecules. Here, we report on the proteolysis of FVIII by alloantibodies of two patients with severe hemophilia A, demonstrating a previously unknown mechanism by which FVIII inhibitors may prevent the pro-coagulant function of FVIII. The kinetic parameters of FVIII hydrolysis indicate a functional role for the catalytic immune response in the inactivation of FVIII in vivo. The characterization of alloantibodies against FVIII as site-specific proteases may provide new approaches to the treatment of FVIII inhibitors.

Antibodies, Catalytic↗
PubMed1999

Restoration of normal interleukin-2 production by CD4+ T cells of human immunodeficiency virus-infected patients after 9 months of highly active antiretroviral therapy.

The present study investigated immune restoration in patients at intermediate stages of human immunodeficiency virus (HIV) disease after initiation of highly active antiretroviral therapy (HAART). A progressive increase in both memory and naive CD4+ T cells was observed from the first weeks of therapy, concomitant with a decrease in the expression of activation markers on CD8+ T cells. The early-activation marker CD69 remained, however, overexpressed on T cells after suboptimal stimulation in vitro, indicative of persistent immune activation. The percentage of interleukin (IL)-2-producing CD4+ T cells significantly increased from 9 months of HAART. In most patients, CD4+ T cells recovered an ability to produce IL-2 on stimulation, similar to that of HIV-seronegative controls. Reversal of T-cell anergy may be a key event in immune restoration for achieving long-term clinical benefit with HAART.

Adult↗
PubMed1998

Therapeutic preparations of normal polyspecific IgG (IVIg) induce apoptosis in human lymphocytes and monocytes: a novel mechanism of action of IVIg involving the Fas apoptotic pathway.

Therapeutic preparations of normal human IgG for i.v. use (i.v.Ig) exhibit a broad spectrum of immunoregulatory activities in vitro and in vivo. I.v.Ig has been shown to inhibit the proliferation of activated B and T lymphocytes and of several autonomously growing cell lines. In this study, we demonstrate that i.v.Ig induces apoptosis in leukemic cells of lymphocyte and monocyte lineage and in CD40-activated normal tonsillar B cells, involving, at least in part, Fas (CD95/APO-1) and activation of caspases. I.v.Ig-induced apoptosis was higher in Fas-sensitive HuT78 cells than in Fas-resistant HuT78.B1 mutant cells, and soluble Fas inhibited IVIg-induced apoptosis. I.v.Ig immunoprecipitated Fas from Fas-expressing transfectants and recognized purified Fas/glutathione-S-transferase fusion proteins upon immunoblotting. Affinity-purified anti-Fas Abs from i.v.Ig induced apoptosis of CEM T cells at a 120-fold lower concentration than unfractionated i.v.Ig. Inhibitors of cysteine proteases of the caspase family, caspase 1 (IL-1beta-converting enzyme) and caspase 3 (Yama/CPP32b), partially inhibited i.v.Ig-induced apoptosis of CEM cells. Furthermore, cleavage of poly(A)DP-ribose polymerase into an 85-kDa signature death fragment was observed in CEM cells following i.v.Ig treatment. Thus, normal IgG induces apoptosis in lymphocytes and monocytes. Our results provide evidence for a role of Fas, bring new insights into the mechanisms of action of i.v.Ig in autoimmune diseases, and suggest a role of normal Ig in controlling cell death and proliferation.

Animals↗
PubMed1998

Early regression of cervical lesions in HIV-seropositive women receiving highly active antiretroviral therapy.

OBJECTIVE: Advanced HIV disease is associated with a high prevalence of cervical squamous intra-epithelial lesions (SIL) and of infection with oncogenic human papillomavirus (HPV) genotypes. Triple-combination antiretroviral therapy results in decreased plasma HIV viral load, increased CD4 cell counts and partial restoration of immune functions in patients with severe HIV disease. This study investigated the outcome of SIL in HIV-seropositive women undergoing triple combination antiretroviral treatment. METHODS: Forty-nine women who started triple-combination antiretroviral therapy, including a protease inhibitor, were examined prior to and after a median 5-month treatment. We collected cytological, colposcopic and histologic data and assessed the presence of HPV DNA in cervical smears by PCR and Southern blot hybridization (SBH). RESULTS: The prevalence of SIL decreased from 69 to 53% during follow-up (P < 0.0001). Among 13 women who initially presented with high-grade SIL, conversion to lower grade was observed in two women and a full regression to normality was observed in one. Cytology also returned to normality in nine out of 21 women who initially presented with low-grade SIL. The high prevalence of HPV infection as detected by SBH and PCR was similar at the first and second examinations and the same high-risk viral genotypes were identified at both examinations in all infected patients but one. There was a higher increase in absolute CD4 cells in the subgroup of patients whose lesions regressed (99 versus 50 x 10(6)/l, P=0.03). CONCLUSION: Our observations demonstrate that active antiretroviral therapy may result in a reduced prevalence of cervical squamous intra-epithelial lesions despite the absence of clearance of HPV infection.

Adult↗
PubMed1998

Self-reactive antibodies (natural autoantibodies) in healthy individuals.

Antibodies that are present in the serum of healthy individuals in the absence of deliberate immunization with any antigen, are refered to as natural antibodies. A vast majority of natural antibodies react with one or more self antigens and are termed as natural autoantibodies. The importance of natural autoantibodies in immune regulation has long been neglected, since tolerance to self was thought to be primarily dependent on the deletion of autoreactive clones, rather than on peripheral suppressive mechanisms. Clonal deletion and energy cannot account, however, for the prevalence of natural autoreactivity among healthy individuals. It is now well established that autoreactive antibodies and B cells, and autoreactive T cells, are present in healthy individuals, and in virtually all vertebrate species. Autoreactive repertoires are predominantly selected early in ontogeny. Questions pertaining to the role of natural antibodies in the regulation of the immune response and maintenance of immune homeostasis and to the distinction between natural autoreactivity and pathological autoimmunity have not been adequately addressed. Here, we focus on the current knowledge on the physicochemical and functional properties of NAA in man, and the use of NAA for therapeutic intervention. reserved.

Autoantibodies↗
PubMed1998

Discrepant responses to triple combination antiretroviral therapy in advanced HIV disease.

OBJECTIVES: To determine the clinical, virological and immunological outcome in a cohort of unselected patients receiving triple combination therapy for more than 1 year. METHODS: Prospective follow-up of a cohort of 162 unselected, protease inhibitor-naive, antiretroviral-experienced patients with advanced HIV disease, treated with indinavir combined with two nucleoside analogues. RESULTS: The mean CD4 cell count and plasma HIV RNA level in the study group at baseline were 69+/-5 x 10(6)/l and 4.75+/-0.07 log10 copies/ml, respectively. Five per cent of patients died prematurely or were lost to follow-up. Fifty-seven per cent of patients responded to therapy, as assessed by a sustained increase in CD4 cell counts above 50 x 10(6)/l and a decrease in plasma HIV RNA greater than 1 log10 copies/ml, throughout 12.1 months of follow-up. Seventeen per cent of patients were immunological and virological non-responders. Twenty-one per cent of patients exhibited discrepant virological and immunological responses to treatment, of whom one-half failed to exhibit significant increases in CD4 cells despite a virological response to therapy and one-half exhibited increased CD4 cell counts in the absence of significant decrease in plasma viral load. The incidence of AIDS-defining events in the latter group of patients was similar to that of responder patients, whereas their incidence was higher in patients who failed to exhibit a virological and immunological response and those who failed to increase CD4 cells despite a significant decrease in viral load. CONCLUSION: Our observations of discrepant immunological and virological responses to treatment raise the issue of the significance of persistent elevated levels of plasma HIV RNA and of the relevance of measurements of plasma viral load for assessing the efficacy of antiretroviral therapy in patients whose CD4 cell counts increase despite the absence of significant decrease in plasma HIV viral load.

Adult↗