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J N Goldman

Publications and source records attributed to J N Goldman.

At least 19 recordsLinked to original sources
PubMed1995

Measles virus persistence in an immortalized murine macrophage cell line.

Persistent infection with the Edmonston strain of measles virus (MV) has been established in IC-21 cells, an immortalized murine macrophage cell line. Persistence was established immediately without syncytia formation or cytopathic effects. MV was expressed in the majority of the cells as evidenced by immunofluorescence microscopy, flow cytometry, infectious centers assays, and limiting dilution analysis. Hemagglutinin (H) and phosphoprotein expressed in persistently infected IC-21 cells had retarded migration in SDS-PAGE gels when compared to these proteins expressed in Vero cells. H protein differences were also found between freshly infected IC-21 cells and persistently infected IC-21 cells passaged for over 2 years. Six sublines of IC-21 cells, infected at different times, have maintained these characteristics for 2 years of passage. During this time period the intensity of immunofluorescence and the number of infectious virus particles recoverable fluctuated in five of the six cell lines. In one cell line virus expression remained at a consistent high level. The ability to establish a persistent MV infection in murine macrophages allows studies using a cell important in disseminating the infection. It facilitates experiments on immunological aspects of viral immunity by enabling cell mixing experiments with histocompatible cell populations and by making available the wide array of cellular and humoral reagents in the mouse.

Animals↗
PubMed1995

Suppression of measles virus expression by noncytolytic antibody in an immortalized macrophage cell line.

Immune regulation of measles virus (MV) expression was studied in a persistently infected mouse macrophage cell line. Synthesis of both membrane-associated and internal MV antigens was suppressed when infected macrophages were treated with polyclonal rabbit anti-MV antibody that was specific for MV proteins. Persistently infected macrophages were treated for 3, 5, or 7 days with increasing doses of anti-MV antibody. All MV proteins were down-regulated 2 days after treatment was terminated. One week after treatment was terminated, down-regulation was still evident but to a lesser degree. MV protein synthesis was suppressed whether or not complement components were inactivated by heating all serum supplements and antibodies. However, when complement was active, cell lysis accounted for some of the reduced MV protein synthesis. When lytic destruction of infected cells by antibody and complement was prevented by inactivation of complement, antibody alone reduced the cellular synthesis of viral proteins by noncytolytic mechanisms. The absence of cell death in the absence of complement was confirmed by the lack of 51Cr release from labeled cells, the lack of reduction in cell number, and the lack of a decrease in total protein synthesis when radiolabeled infected cells were treated with antibody. It is noteworthy that low doses of antibody were optimal for suppression in the longer-term experiments and did not cause lysis, even in the presence of active complement. Since infected macrophages disseminate virus in measles infection, noncytolytic regulation of these cells by antibody may supplement viral clearance by cytolytic T cells and other immune mechanisms.

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PubMed1992

T lymphocytes mediate immunologic control of C3 gene expression.

Immunologic control of C3 gene expression by tissue macrophages can be accomplished by treatment of spleen fragments with anti-C3 antibody. We now demonstrate that suppression of C3 requires participation of T lymphocytes of both the CD4+ and CD8+ phenotypes. Pretreatment of splenic tissue with anti-Thy-1.2 monoclonal antibody blocks the ability of the anti-C3 antibody to induce C3 suppression. Reduction in either the CD4+ or CD8+ subpopulations of T lymphocytes also abrogates C3 suppression demonstrating that both T cell subsets are required in addition to the inducing antibody. Artificially elevating intracellular levels of cAMP with cholera toxin can partially substitute for the effects mediated by T cells in this reaction. Therefore, normal expression of the C3 gene can be suppressed by a regulatory network that requires the presence of a specific inducing antibody and T lymphocytes of both the CD4+ and CD8+ subsets. This regulatory network has many similarities to regulatory networks that have been well documented in suppression of specific murine immunoglobulin allotypes.

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PubMed1991

Immunologic control of C3 gene expression in tissue macrophages.

Antigenic suppression of individual complement components can be induced when newborn animals or cells in tissue culture are treated for a period of time with antibody directed against that component. The initial exposure to antibody induces a network involving regulatory lymphocytes and soluble factors. Antigenic suppression has been accomplished either in vivo or in vitro with all three members of the evolutionarily related family C3, C4, and C5. In this report we have demonstrated that antigenic suppression is mainly the result of posttranscriptional regulation. After antibody treatment is terminated, during a period in which C3 protein is undetectable by sensitive assays, C3 mRNA is often briefly increased, after which it is modestly reduced. Therefore, the major mechanisms mediating immunologic control of C3 synthesis and secretion are not directly related to steady-state levels of C3 mRNA. The initially increased levels of C3 mRNA prove that there is no simple direct quantitative relationship between C3 mRNA and C3 synthesis and secretion. The later decreases in C3 mRNA levels are not sufficient to explain the quantitatively greater decreases in C3 synthesis. Therefore, the rate determining step in immune regulation of C3 production occurs after transcription. Regulation could be mediated by altered stability of C3 mRNA in the presence of antibody, formation of a defective primary transcript, defective processing of the transcript resulting in an abnormal mRNA, or a defective C3 translational apparatus. Although regulation is multifactorial, interference with translation is most likely to predominate.

Animals↗
PubMed1988

Effects of anti-C4 antibody on complement production by splenic and peritoneal macrophages.

We have previously shown that administration of anti-C4 antibody to cells in culture can suppress the synthesis and secretion of C4. Lymphoid cells must be present along with the C4 secreting macrophages to achieve suppression of full magnitude and long duration. In this publication we have demonstrated that treatment of peritoneal macrophages with intact anti-C4 antibody results in reduction of intracellular and secreted C4. Intracellular levels of pro-C4 rapidly returned to normal after removal of the suppressing antibody and extracellular levels of C4 secreted into the media returned to normal within 24-48 h. This is in marked contrast to our previously published results with splenic fragments where intracellular pro-C4 remained markedly reduced long after removal of anti-C4. Using pulse-chase experiments we now demonstrate that, after recovery from suppression, intracellular pro-C4 levels remain low in splenic macrophages because nascent C4 is processed through the cell more rapidly. This results in a smaller intracellular pool of C4, even in the face of normal or high levels of C4 synthesis in the postsuppression phase. Finally, we demonstrate that suppression of full magnitude and duration could only be achieved with intact anti-C4 antibody. F(ab')2 fragments were not capable of inducing complete suppression.

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PubMed1987

The role of lymphoid cells in antibody-induced suppression of the fourth component of guinea pig complement.

Many laboratories have demonstrated that immunoglobulin production by B cells is controlled by networks of interacting lymphocytes and their products. Our laboratory has demonstrated that complement components produced by macrophages are also regulated by networks of interacting cells and humoral factors. Treatment of mice in vivo or guinea pig cells in vitro with anticomponent antibody specifically inhibits synthesis and secretion of the component by macrophages. We have further characterized the cellular basis for in vitro suppression of the fourth component of guinea pig complement. C4 suppression has been accomplished with dispersed spleen cells as well as intact splenic fragments. This facilitated examination of the cells responsible for long-term C4 suppression. The data suggested that C4 suppression required either cell contact or sufficient concentrations of soluble factors. Long-term suppression of C4 depends upon a lymphoid cell contained in the spleen and in lymph nodes but absent or in insufficient concentration in the peritoneum. The lymphocyte that actively maintains suppression was negative for the guinea pig T-cell marker detected by the monoclonal antibody mc8BE6. Therefore, the critical cell is either another T-cell subset or non-T lymphocyte. These data demonstrate that a network of interacting cells analogous to that proposed to regulate antibody synthesis is also involved in regulating some nonlymphoid cell products.

Animals↗
PubMed1986

Murine sex-limited protein expression requires androgens and pituitary hormones.

Levels of the murine sex-limited protein (Slp) were measured by an enzyme-linked immunosorbent assay in normal and hypophysectomized female CDF1 (Slpa) mice before and after a 15-day treatment with testosterone proprionate. Both groups of mice initially had undetectable levels of circulating Slp. After treatment, Slp serum levels of the nonhypophysectomized group had risen significantly above the Slp serum levels of the hypophysectomized group and the pretreatment controls. This indicates that the pituitary gland is necessary for the androgen-induced expression of Slp.

Animals↗
PubMed1985

Antibody-induced suppression and postsuppression stimulation of complement in vitro. III. Long-term C4 suppression is actively maintained by a soluble suppressor factor (FsC4).

Previous work in our laboratory established that individual complement components can be regulated in vivo by administration of specific antibody or immunocompetent cells to newborns and in vitro by administration of specific antibody to cultured peritoneal macrophages or splenic fragments. Antibody-induced suppression of C4 was much longer lasting in cultured guinea pig splenic fragments than in cultured guinea pig peritoneal macrophages, suggesting that splenic fragments contained elements necessary for long-term suppression that were not present in the macrophage monolayers. This publication presents data in support of this concept. Antibody-treated splenic fragments from normal guinea pigs--but not from C4-deficient guinea pigs--elaborated a soluble factor (FsC4) that suppressed C4 production in previously untreated splenic fragments. FsC4 activity was most potent in splenic fragment culture supernatants at those times when intracellular and secreted C4 hemolytic activity and C4 antigen were at their lowest. C4 itself or a fragment of C4 was therefore unlikely to mediate suppression in this system. Residual anti-C4 antibody was ruled out as a mediator of FsC4 activity since it was shown by two independent methods that the amount of anti-C4 antibody carried over with the supernatant was orders of magnitude less than the amount necessary to cause suppression or to neutralize fluid phase C4 in fresh splenic fragment cultures. Preliminary data revealed that FsC4 activity may be mediated by two or more distinct molecular species or may be mediated by a single molecule that exhibits secondary size and charge heterogeneity. The identification of factors that are capable of regulating C4 suggests that, as with immunoglobulins, complement components may be regulated by complex networks of immunocompetent cells and their soluble products.

Animals↗
PubMed1985

Enhancement by cyclic AMP of antibody-induced suppression of the fourth component of complement.

Our laboratory has shown that short-term treatment in vivo or in vitro with monospecific antibody to individual complement components can have long-term effects on the production of those components. In vitro studies have focused on the fourth component of complement (C4) in a guinea pig model. Uniform splenic fragments have been used to mimic the in vivo microenvironment of the C4-producing macrophages. A 4-day exposure to anti-C4 antibody led to a reduction of secreted C4 for 1 to 2 wk and a reduction of intracellular C4 that persisted even longer. In an attempt to understand how short-term exposure to antibody can specifically and permanently disrupt the C4-producing cell, we have determined whether C4 suppression could be enhanced by components that modulate cellular functions through their role as secondary intracellular messengers. We found that compounds which elevated cellular levels of cAMP by any of three mechanisms all enhanced antibody-induced suppression of C4.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Antibody-induced suppression and postsuppression stimulation of complement in vitro. II. Intracellular and extracellular changes in C4 during long-term C4 suppression in guinea pig splenic fragments.

Suppression of the synthesis of the fourth component of complement in vitro was originally accomplished by exposing cultured guinea pig peritoneal cells to anti-C4 alloantisera. When guinea pig splenic fragments were used instead of peritoneal cells, equivalent antibody treatment produced C4 suppression of significantly longer duration, lasting weeks instead of days after removal of antibody. As with peritoneal cell monolayers, antibody treatment induced specific suppression of C4 followed by nonspecific stimulation of C4 and other proteins such as C2. Although IgG2 is more readily sequestered by splenic tissue, both IgG1 and IgG2 antibodies were effective in inducing and maintaining suppression. Experiments with radiolabeled antibody demonstrated that a small amount (less than 5%) of the original dose of antibody was retained by the splenic fragments. Because there was no continuous slow release of that antibody, long-term suppression of C4 cannot be explained as a fluid-phase neutralization reaction. Because antibody treatment might induce production of aberrant C4 molecules with no functional activity, C4 antigens was also studied. Tissue culture supernatants were assayed by using an ELISA for C4. In none of these experiments was extracellular C4 antigen detectable immediately after antibody treatment. Extracellular and intracellular C4 were immunoprecipitated from biosynthetically labeled tissue cultures and analyzed by SDS-PAGE. Antibody treatment suppressed intracellular C4 as well as extracellular C4. Although extracellular C4 levels of antibody-treated cultures eventually returned to levels comparable to untreated cultures, intracellular C4 levels of treated fragments remained lower than controls for the full period of observation (22 days). Therefore, a short (4-day) exposure to anti-C4 antibody induced long-term effects that profoundly altered regulation of C4 synthesis and secretion by cultured splenic macrophages.

Animals↗
PubMed1984

Enhancement of macrophage survival and complement production by factors from cloned T cells.

The addition of supernatants of some cloned mouse T cell lines to guinea pig peritoneal cells in tissue culture increased the production of the second (C2) and fourth (C4) components of complement as well as the enzyme beta-glucuronidase. Enumeration of cell populations demonstrated a simultaneous increase in cell survival. Supernatants that augmented functions of the cultured cells were obtained after alloantigen stimulation of a T cell line of C57BL/6 origin termed L2, but supernatants from a variant cell line derived from L2 and termed L2V had no effect. A delay of as little as 24 h in the addition of L2 T cell factors at the start of the cultures markedly diminished the effects on the cultured cells that were ordinarily observed 1-2 weeks later. These experiments suggest that, in this xenogenic system, complement-enhancing activity is part of a general stimulation of macrophages by cloned T cell factors.

Animals↗
PubMed1982

Genetic control of C6 polymorphism and C6 deficiency in rabbits.

The genetic control of the sixth component of complement (C6) in rabbits has been studied by quantitation of C6 functional and antigenic levels and identification of polymorphism by isoelectric focusing (IEF) in gels. Patterns of inheritance of C6 variants in families carrying a silent gene for C6 were examined, and it was found that 3 common plasma phenotypic variants, C6 A, C6 B, and C6 QO were under the genetic control of allelic genes, C6*A, C6*B, and C6*QO. In IEF patterns, C6 A could be identified by its isoelectric point that was slightly more acidic than that of C6 B. C6 QO was undetectable because it lacked functional and antigenic activity. The C6*A/C6*B genotype displayed a mixed IEF pattern with bands characteristic of both C6 A and C6 B. Functional and antigenic levels of C6 that were found in heterozygous C6*A/C6*QO and C6*B/C6*QO rabbits were approximately one-half of the C6 levels found in the corresponding homozygous animals. The phenotypic variation closely resembles that previously observed in humans and rhesus monkeys, as well as preliminary data in rabbits. The patterns of inheritance indicated that the two common C6 structural genes and the deficiency gene were allelic variants at the same genetic locus.

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