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S H Pincus

Publications and source records attributed to S H Pincus.

At least 19 recordsLinked to original sources
PubMed1992

Effect of H chain V region on complement activation by immobilized immune complexes.

Activation of C by immune complexes (IC) in tissues and the inflammatory consequences are major determinants in the pathogenesis of many autoimmune disorders. To assess the factors involved in C activation by such IC, we examined the binding of C components by chimeric IgG1 antibodies bound to immobilized Ag. We previously reported that alterations in the H chain V regions can affect the binding of first component of C (C1q) and a major breakdown product of the third C component (C3b) when otherwise identical antibodies were bound to immobilized (Tyr, Glu)-Ala-Lys. To evaluate C activation of these antibodies in well defined IC, we utilized a 9-amino acid peptide conjugated to BSA as Ag. The peptide:BSA conjugate was bound similarly by the two IgG1 antibodies which differed mainly in the CDR3 regions, but also in 9 other amino acids in the H chain V region. When soluble IC were prepared with the two antibodies, they activated C similarly. However, C activation by solid phase Ag:antibody complexes differed; we found that antibody 10B bound more C1q and C3b than antibody B11 did, unless the Ag was present at high density on the plates. These data suggest that the variable region differences affect C activation by these antibody when they are bound to immobilized Ag. Furthermore, these results underscore the differences in C activation by the same antibody depending upon whether the IC are free in solution or immobilized.

Amino Acid Sequence↗
PubMed1992

Eosinophils as host cells for HIV-1.

Transient expression of HIV-1 p24 antigen was observed in eosinophils acutely infected with the HTLV-IIIB strain of HIV-1. PCR analysis of eosinophils isolated from 18 seropositive individuals showed HIV-1 sequences to be present in 2 subjects. These data suggest that eosinophils may act as host cells for HIV-1.

DNA, Viral↗
PubMed1992

A defect in the humoral immune response to protein antigens and haptens in immunoglobulin mu heavy-chain transgenic mice.

We have examined the antibody response in mice expressing a functionally rearranged mu Ig heavy chain derived from a hybridoma antibody with specificity for the hapten 4-hydroxy-3-nitrophenyl (NP). Transgenic mice and their normal littermates were immunized with the antigens NP-OVA, the synthetic polypeptide (Tyr,Glu)-Ala-Lys ((T,G)-A-L), or saline. The presence of serum antibodies to NP-BSA, OVA, (T,G)-A-L, and BSA was examined by ELISA. Sera were evaluated prior to immunization and at periods of up to 4 months following immunization. Prior to immunization, transgenic mice had high levels of IgM anti-NP antibody but no detectable antibody to the other antigens. Both the primary and secondary antibody responses of transgenic mice to NP, OVA, and (T,G)-A-L were depressed when compared with the response of non-transgenic mice. Because of reports that these transgenic mice have increased proportions of CD5 + B-cells, a subpopulation associated with the production of autoantibodies, we examined these mice for the production of both IgG and IgM rheumatoid factors and anti-DNA antibodies. Transgenic mice had a modest increase in the spontaneous production of IgM anti-DNA. These data demonstrate a functional defect in the humoral immune response of mu transgenic mice.

Animals↗
PubMed1992

The interplay of microbes and their hosts.

Microbes and their hosts exert considerable evolutionary pressure on one another. This brief report of a recent meeting describes the strategies and tactics, and highlights some of the key molecules involved in the complex host-parasite relationship.

Animals↗
PubMed1992

Group B streptococcal opacity variants.

Colony opacity variants were detected for type III group B streptococci (GBS). Transparent colonies predominate in the parent GBS, with occasional colonies having opaque portions. Two stable opaque variants (1.1 and 1.5) were compared with three transparent clones (1.2, 1.3, and 1.4). All grew well on blood agar and on GC medium, but variant 1.1 failed to grow on Todd-Hewitt medium. Scanning and transmission electron microscopy demonstrated that colony opacity correlated with bacterial aggregation status, with opaque variants forming longer and more organized chains. Opaque-transparent switches were observed in both directions for most variants, with transparent to opaque noted most frequently, but 1.5 did not switch at all. Switching of the opacity phenotype was observed both in vitro and in neonatal mice. Relationships between colony opacity and several cell surface phenomena were explored. (i) Opaque variant 1.1 had two surface proteins (46 and 75 kDa) that were either unique or greatly overexpressed. (ii) Variant 1.1 was deficient in type III polysaccharide, while 1.5 lacked group B antigen. Diminished capsular polysaccharide of variant 1.1 was reflected in reduced negative electrophoretic mobility and in increased buoyant density. (iii) Transparent variant colonies growing closest to a penicillin disk were opaque, but colonial variants did not differ in their sensitivity to penicillin. These data indicate that GBS can exist in both opaque and transparent forms, with opaque appearance occurring by multiple routes. Opaque variants grow poorly on Todd-Hewitt medium generally used for isolation of GBS, so any possible relationships between opacity variation and pathogenesis of GBS infection are unknown.

Bacterial Capsules↗
PubMed1992

In situ localization of interleukin-6 in normal skin and atrophic cutaneous disease.

Interleukin-6 (IL-6) is a multifunctional cytokine that participates in the inflammatory and immune responses. In human skin, keratinocytes produces IL-6, although the in vivo role of this cytokine is unknown. In the present study we investigated the in situ localization of IL-6 in normal epidermis (n = 10) and in a group of skin diseases characterized by epidermal atrophy. Formalin-fixed paraffin-embedded skin biopsies from patients with clinical and histopathological features consistent with localized scleroderma (n = 10), systemic scleroderma (n = 5), lichen sclerosus et atrophicus (n = 9) and balanitis xerotica obliterans (n = 7) were tested using polyclonal antibodies and avidin-biotin-peroxidase immunostaining. We demonstrated the presence of IL-6 in normal epidermis and in atrophic skin diseases. In normal skin there was moderate intercellular and intracellular reactivity detected using a high antibody concentration. In specimens with epidermal atrophy we detected intense cytoplasmic and intercellular immunostaining using a lower antibody concentration. The immunoreactivity was independent of the epidermal thickness. Plasma IL-6, measured by radioimmunoassay, was not elevated in plasma from patients with localized or systemic scleroderma. Increased IL-6 in the epidermis of selected skin diseases suggests that IL-6 may be related to the pathophysiology of dermatologic diseases characterized by epidermal atrophy.

Antibody Specificity↗
PubMed1992

Selective regulation of eosinophil degranulation by interleukin 1 beta.

Recent evidence confirms that cytokines such as IL-1, IL-4, IL-5, and GM-CSF may enhance or inhibit eosinophil function. Functions that are susceptible to modulation include eosinophil-mediated antibody-dependent damage of helminthic parasites, oxidative metabolism and degranulation. We have employed IgG and IgE-coated Sepharose beads to investigate selective modulation of IgG and IgE-mediated enzyme release by IL-1 beta. Both IgG and IgE-coated beads induced release of granular enzymes beta-glucuronidase and arylsulfatase. Enzyme release from IgG-stimulated eosinophils was inhibited by preincubation with IL-1 beta (100 pg/ml, P less than or equal to 0.05). In contrast, enzyme release by IgE-stimulated eosinophils was enhanced by IL-1 beta (100 pg/ml, P less than or equal to 0.05). These studies support the hypothesis that IL-1 beta has specific selective actions on eosinophil function. Furthermore, these actions on particle-stimulated enzyme release suggest that IgG and IgE mediated processes in eosinophils are differentially regulated.

Arylsulfatases↗
PubMed1992

Variable region differences affect antibody binding to immobilized but not soluble antigen.

We have examined the antigen binding characteristics of two chimeric IgG1 antibodies that differ only in the heavy chain variable region. Antibodies 10B and B11 were expressed from two different anti-(Tyr,Glu)-Ala-Lys murine VH genes joined to human IgG1 constant region genes in a murine anti-(Tyr,Glu)-Ala-Lys heavy chain loss variant hybridoma. The binding characteristics of the antibodies to (Tyr,Glu)-Ala-Lys and to a peptide conjugate, CYYYEEEEY:BSA, were measured in solution and solid phase assays. The antibodies exhibited similar affinities and binding characteristics when assayed in solution assays. However, when we measured binding of antibodies to immobilized antigens, we found that antibody affinity depended on the epitope density in the immobilized immune complexes. The binding of antibody 10B and of B11 to immobilized (Tyr,Glu)-Ala-Lys and to CYYYEEEEY:BSA were similar at high antigen density, but antibody B11 bound less well at lower antigen density. Fab fragments of 10B bound to immobilized (Tyr,Glu)-Ala-Lys and CYYYEEEEY:BSA, but Fab fragments of B11 did not bind to (Tyr,Glu)-Ala-Lys and bound less well to CYYYEEEEY:BSA than 10B Fabs.

Amino Acid Sequence↗
PubMed1992

Vulvar dermatoses and pruritus vulvae.

This article has attempted to summarize the various causes of vulvar pruritus and present a framework for evaluating these patients. Although not all patients have a readily classifiable disorder, symptomatic treatment and reassurance can provide considerable patient relief. There is no easy answer, yet the recognition that the process is treatable, if not curable, should provide encouragement for both patients and their physicians.

Chronic Disease↗
PubMed1991

In vitro efficacy of anti-HIV immunotoxins targeted by various antibodies to the envelope protein.

Six different anti-HIV envelope antibodies and one irrelevant control antibody were coupled to ricin A chain and tested for their efficacy in inhibiting HIV tissue culture infections. The anti-HIV antibodies consisted of five monoclonals, three of murine and two of human origin, and one polyclonal preparation prepared by affinity purifying pooled serum antibodies from HIV-infected humans on rgp160. The binding specificity of the antibodies was defined by ELISA by using recombinant envelope proteins and synthetic peptides, and by flow cytometry on HIV-infected cells. The in vitro efficacy of the antibodies was tested by the abilities of the immunotoxins to inhibit protein synthesis in persistently infected cell lines and by their abilities to inhibit HIV production during both acute and persistent infection as measured with an HIV-specific focal immunoassay. The immunotoxins were tested against a panel of distinctly different HIV isolates. The results indicate the following: 1) A mAb to the immunodominant neutralizing loop was highly effective against homologous strains of HIV, but had no activity against heterologous HIV. 2) The efficacy of anti-gp41 mAb varied depending upon the epitope recognized and possibly the affinity of binding to gp41. 3) The polyclonal human anti-gp160 antibodies produced the immunotoxin with the broadest specificity for different HIV strains and the greatest specific activity. This is related to the polyclonal nature of the preparation rather than an increase in relative avidity of the antibody. 4) Activity of an immunotoxin is not a direct function of the binding of the antibody to the surface of infected cells. 5) The ability of an immunotoxin to halt the spread of infection through a tissue culture cell population is dependent upon the ability of the antibody to neutralize the virus as well as the activity of the toxin. Our data suggest that efficacious immunotoxins for the treatment of AIDS may be made with polyclonal anti-envelope antibodies derived from the serum of patients who have been infected with HIV or with appropriately chosen anti-gp41 antibodies.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Use of a focal infectivity assay for testing susceptibility of HIV to antiviral agents.

A highly sensitive and quantitative focal immunoassay has been developed for detecting the human immunodeficiency virus (HIV). The assay can be used to measure cell-free virus or the production of HIV by virus-infected cells. Both laboratory-adapted strains of HIV and patient isolates can be studied with this assay. In this communication, we demonstrate the utility of this assay for measuring the effects of anti-HIV agents on viral isolates. We show that the anti-viral effects of such diverse agents as azidothymidine, interferon-alpha, immunotoxins, soluble CD4 and antibody can be accurately quantified. This assay may be used in the discovery and evaluation of new anti-HIV therapies or may be adapted for use in testing the sensitivity of patient isolates to standard therapeutic agents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Alteration in H chain V region affects complement activation by chimeric antibodies.

Chimeric antibodies to the synthetic polypeptide (Tyr, Glu)-Ala-Lys ((T,G)-A-L) were used to examine C activation by human IgG1. Two IgG1 antibodies, which contained mouse L chains and H chains with mouse V domains and human C domains, differed only in their VH domain. Ag binding and C activation by these antibodies were analyzed by ELISA. When limiting amounts of Ag were used in the assays, the antibodies required different quantities of Ag for optimal binding, suggesting that the antibodies bind to different epitopes on the (T,G)-A-L molecule. However, when competitive inhibition assays were performed with an optimal concentration of Ag, there were no differences in relative binding affinities for (T,G)-A-L or dissociation characteristics of the antibodies. C activation was examined at optimal Ag concentration to ensure equivalent binding of two IgG1 antibodies to Ag. After combination with immobilized Ag, these two antibodies bearing different V regions exhibited marked differences in the binding of C components C1q and C3d. When present in equal amounts in the assay, antibody 10B activated C and bound more C1q and C3d than antibody B11. These results indicate that V region differences can affect C activation by IgG.

Amino Acid Sequence↗
PubMed1990

Variants selected by treatment of human immunodeficiency virus-infected cells with an immunotoxin.

An immunotoxin has been made by coupling anti-human immunodeficiency virus (HIV) envelope antibody 907 to ricin A chain (907-RAC). 907 recognizes an epitope within the immunodominant PB-1 loop of gp120. Variant cells were selected by cloning persistently infected H9/human T lymphocyte virus IIIB cells in the presence of the immunotoxin. Clones resistant to 907-RAC arose at a frequency of 0.1-1.0%. Seven clones were selected for intensive analysis. When studied, these clones fell into two distinct groups, members of which appeared to be identical, suggesting that the variation arose before the selection process. In contrast to the parent cells, none of the cloned variants produced infectious HIV. The first set of clones, designated the "E" variants, expressed decreased levels of the HIV envelope on the cell surface. However, levels of intracellular HIV antigens and reverse transcriptase were equal to or greater than that of the parental cell line. Radioimmunoprecipitation demonstrated that the gp160 was truncated to 145 kD (gp120 was normal length), capable of binding to CD4, and, unlike normal gp160, was released in its unprocessed form into the cellular supernatant. Sequence analysis demonstrated that a deletion at codon 687 of the envelope gene resulted in the production of this truncated protein. Ultrastructural analysis of E variants demonstrated some budding forms of virus, but also large numbers of HIV within intracellular vesicles. The second set of variants, the "F" series, produced no HIV antigens, reverse transcriptase, nor was there ultrastructural evidence of virus. However, proviral DNA was present. Virus could not be induced with agents known to activate latent HIV. These cells also lacked cell surface CD4 and could not be infected with HIV. These studies demonstrate that variation in HIV can affect the phenotype of the cells carrying the altered virus, allowing for escape from immunologic destruction. The E variants may serve as prototypes for attenuated HIV, which could be used as a vaccine. We have reconstructed the mutation found in the E variants within the infectious HIV clone HXB-2 and demonstrated that the resulting virus retains its noninfectious phenotype.

Base Sequence↗
PubMed1990

Inhibition of IgG-triggered human eosinophil function by IL-4.

Triggering of eosinophil secretory and cytotoxic functions by stimulation of the IgG and IgE FcR is thought to have major importance in the pathophysiology of tissue eosinophilia. We studied the ability of human rIL-4 to regulate this triggering event in human eosinophils. At doses ranging from 0.1 to 10 pg/ml, IL-4 suppressed eosinophil secretion of beta-glucuronidase and arylsulfatase by up to 65% after stimulation with IgG-coated Sepharose beads. This effect required prolonged preincubation (16 h) of eosinophils with IL-4; no effect was detected after 1 h preincubation. Enzyme secretion stimulated by IgE-coated beads was not affected. Further, IL-4 (after 16 h preincubation), suppressed eosinophil antibody-dependent killing of schistosomula (Schistosoma mansoni) targets by 24 to 39% in four experiments (p less than 0.05). Flow microfluorimetry analysis showed that IL-4 reduced the expression of IgG FcR, but not IgE FcR, suggesting that this mechanism underlies the suppression of IgG-mediated secretion. Taken collectively, these results demonstrate a mechanism for T lymphocyte suppression of IgG-stimulated eosinophil functions via IL-4.

Animals↗
PubMed1990

AZT demonstrates anti-HIV-1 activity in persistently infected cell lines: implications for combination chemotherapy and immunotherapy.

A sensitive and quantitative focal immunoassay has been used to measure the effects of three different therapeutic agents on tissue culture cells infected with human immunodeficiency virus (HIV). The effects of the drugs were studied on both acutely and persistently infected CD4+ cell lines. The three agents, azidothymidine (AZT), interferon-alpha (IFN-alpha), and an anti-HIV envelope antibody coupled to ricin A chain, were tested alone and in combination. AZT was found to have its greatest effect during early stages of the infection, but also had an action on persistently infected T cell lines. The effect of AZT on persistently infected cells was seen within 24 h, increased with extended exposure to the drug, and persisted after its removal. IFN-alpha had variable effects on acutely infected cells but suppressed chronic infection. Combinations of the therapeutic agents were studied. Using a model that allowed for treatment during both acute and persistent stages of infection, the most effective combination in suppressing HIV infection was the continual use of both AZT and IFN-alpha at the highest tolerable doses. Knowledge of the efficacy of AZT on persistently infected cells will allow for the most effective design of clinical protocols.

Cell Line↗
PubMed1990

In vivo administration of interferon-gamma to patients with rheumatoid arthritis decreases numbers of circulating B cells.

We evaluated the expression of leukocyte cell surface antigens in patients with rheumatoid arthritis (RA) and healthy individuals using monoclonal antibodies and flow cytometry. Both 1 and 2-color analyses were performed. Markers evaluated included markers of T and B cell subsets, activation antigens, and antigens expressed on additional cell types. No major differences were seen between healthy persons and patients. The effects of in vivo administration of interferon-gamma (IFN-gamma) were studied in a clinical trial of the efficacy of this agent in the treatment of RA. Numbers of circulating B cells fell with administration of IFN-gamma. Expression of HLA-DR antigens on monocytes may have increased slightly with IFN therapy. There was no correlation between clinical response to IFN-gamma and change in any immune variables. Because of the observed alterations in B cell numbers, serum immunoglobulins were measured by radial immunodiffusion. There was no alteration of levels of most immunoglobulin isotypes as a result of therapy. There was a modest increase in serum IgA. There was no change in either rheumatoid factor or antinuclear antibody titers during IFN-gamma therapy.

Antibodies, Monoclonal↗