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M G Goodman

Publications and source records attributed to M G Goodman.

At least 55 records · Page 3Linked to original sources
PubMed1984

Regulation of B-lymphocyte proliferative responses by arachidonate metabolites: effects on membrane-directed versus intracellular activators.

Immunoregulatory effects of the oxidative metabolites of arachidonic acid (AA) on proliferation of B-lymphocytes were assessed in a serum-free culture system. Activation of B cells by membrane-directed ligands and intracellular activators was regulated by AA metabolites in very distinct fashions. Thus exogenous cyclooxygenase products (particularly prostaglandins E1 and E2) amplified the response to anti-immunoglobulin antibodies, whereas lipoxygenase products damped this response. In contrast, B cell activation with 8-mercaptoguanosine (an intracellular activator) was inhibited by cyclooxygenase products and remained relatively unaffected by several lipoxygenase products tested. This pattern of results was confirmed in studies with pathway inhibitors. Moreover, when liberation of endogenous AA was induced by stimulation of phospholipase A2 activity with melittin, inhibition of the response to each class of activator was counteracted with the appropriate pathway inhibitor. Results suggest that the two major groups of AA oxidation products function as a system of counterbalancing regulatory influences, serving to modulate B cell activation at the plasma membrane and to downregulate B cell activation at the intracellular level.

Animals↗
PubMed1984

Intracellular lymphocyte activation and carrier-mediated transport of C8-substituted guanine ribonucleosides.

The studies described in this report constitute evidence substantiating that certain exogenous nucleoside derivatives can activate lymphocytes by acting intracellularly. These molecules, the C8-substituted guanine ribonucleosides, have recently been demonstrated to exert potent immunostimulatory and immunoregulatory activities both in vitro and in vivo. The current studies were undertaken to investigate whether the site of induction of mitogenesis in murine B lymphocytes by these compounds was intracellular or at the plasma membrane. Uptake of 8-bromoguanosine was found to proceed by carrier-mediated transport. Like that described for adenosine, the uptake system for 8-bromoguanosine could be resolved into high-affinity and low-affinity components. The hypothesis that the C8-substituted guanine ribonucleosides act intracellularly was tested in several ways. Immobilization of these substituted nucleosides, either on Sepharose beads or in the form of high molecular weight polymers, resulted in total loss of their mitogenicity. In addition, maneuvers designed to diminish plasma membrane fluidity interfered with transmembrane signaling by surface membrane-directed mitogens far more than they did with activation by the substituted nucleosides. Furthermore, modulation of surface membrane protein (IgM) with anti-IgM antibodies similarly resulted in differential inhibition of transmembrane signals with relatively little effect on activation by 8-mercaptoguanosine. Taken together, these data are consistent with the hypothesis that the C8-substituted guanine ribonucleosides trigger the cell at an intracellular site.

Animals↗
PubMed1984

Mechanism of 8-mercaptoguanosine-mediated adjuvanticity: roles of clonal expansion and cellular recruitment.

The mechanism by which increased numbers of antigen-responsive B cells are generated in the presence of antigen and the C8-substituted guanine ribonucleoside, 8-mercaptoguanosine (8MGuo), has been investigated. Augmentation of the primary humoral response of splenocytes to antigen cannot be ascribed to the additive effects of the underlying antigen-specific response and the nonspecific (polyclonal) response induced by 8MGuo. This is clear from a consideration of the magnitude of the responses involved, as well as from a murine model (the SJL mouse) that does not generate a nonspecific response to the substituted nucleoside but responds to it with the usual degree of immunoenhancement in the presence of antigen. Other approaches suggest that two mechanisms are involved in adjuvanticity, one whereby preexisting antigen-specific B cells undergo clonal expansion, and one in which cells not normally participating in the response are recruited in the absence of clonal expansion. The latter mechanism appears to be the dominant one insofar as models in which 8MGuo-induced proliferation fails to occur (such as after irradiation, or in the SJL mouse) nonetheless exhibit strong adjuvant effects. Analysis of precursor frequency of antigen-specific B cells indicates that for each mature, antigen-responsive B cell present in adult murine spleen, an average of four additional cells can be recruited by the conjoint actions of antigen and 8MGuo. One group subject to such recruitment is the immature antigen-specific B cell, whose degree of functional maturity is accelerated in the presence of antigen and 8MGuo.

Adjuvants, Immunologic↗
PubMed1984

Monokine generation as a consequence of binding of human C5a anaphylatoxin to specific cell-surface receptors.

The addition of human C5a to antigen-stimulated cultures results in dose-dependent augmentation of the primary antibody response to antigen. The specificity of this effect is confirmed by the ability of C5ades Arg, but not of the structurally analogous C3a anaphylatoxin, to act in a parallel fashion. This effect appears to be mediated by interaction of C5a with cells of the monocytoid/macrophage lineage. These cells have been shown to bear surface receptors specific for C5a. In order to examine the role of soluble mediators in these events, culture supernatants were generated from splenic adherent cells or macrophage cell lines after exposure to a brief pulse of human C5a. Supernatants from the macrophage-like cell line P388D1, which bears surface receptors for C5a, enhance the PFC response to antigen, whereas those from the closely related cell line P388, which lacks surface receptors for C5a, fail to cause enhancement. Supernatants from splenic adherent cells, which also bear C5a receptors, similarly augment the SRBC response. Active supernatants, but not those devoid of activity, contain IL-1 activity. None of the supernatants contain IL-2 activity. These observations suggest that the recently described role of human C5a as an immunopotentiating modulator is mediated by its ability to induce production of IL-1 upon binding to specific receptors at the macrophage cell surface.

Antibody Formation↗
PubMed1984

Demonstration of activation-specific interactions among B lymphocyte membrane proteins by a photoreactive cross-linking agent.

The formation of plasma membrane protein complexes during B cell activation was examined by covalently stabilizing these complexes with a photolabile, cleavable, cross-linking reagent, dithiobisphenylazide (DTPA). Analysis by SDS polyacrylamide gel electrophoresis indicates that LPS induces a time-dependent rearrangement in membrane proteins of splenic B cells. These rearrangements were localized to the plasma membrane by examination of surface-labeled detergent lysates and purified plasma membrane preparations. DTPA-stabilized rearrangements could be detected as early as 15 min and were stable between 3 and 24 hr after mitogen addition. These changes are consistent with the formation of different functional protein complexes during B cell activation. LPS does not induce membrane protein rearrangement in thymocytes, nor does Con A do so in B cells. Therefore, the changes appear to be correlated with the transmission of a relevant activation signal. Activation of B cells with 8- bromoguanosine ( 8BrGuo ), an intracellular mitogen, did not result in protein rearrangement until 12 hr after mitogen addition, suggesting that initial stages of signal transduction by 8BrGuo and LPS follow separate pathways. A common "activated state" of the membrane is established by 12 hr. Inhibition of de novo protein synthesis by cycloheximide did not interfere with formation of new protein complexes during early stages of activation (15 min and 3 hr). These data indicate that covalent cross-linking with DTPA can be used to demonstrate activation-specific interactions among proteins on the surface membrane of B cells.

Animals↗
PubMed1983

Manifold amplification of in vivo immunity in normal and immunodeficient mice by ribonucleosides derivatized at C8 of guanine.

Antigen-specific lymphocyte activation is generally thought to be initiated by the binding of antigen to specific membrane receptors, followed by transduction of a signal across the cell membrane. In addition, at least two supplementary signals apparently are required for induction of specific antibody synthesis. Various exogenous agents have been shown to augment the magnitude of specific responses to antigen. Certain of these adjuvants are polyclonal activators as well. We recently described a new class of activator, the C8-substituted-guanine ribonucleosides, that traverses the cell membrane and bypasses classical triggering mechanisms to activate the lymphocyte at an intracellular site. The current studies demonstrate that this new class of activator exerts powerful in vivo adjuvant activity when administered to mice after antigen. This effect is highly dose- and time-dependent. When nucleoside administration is delayed until 3-4 days after immunization, enhancement of the response persists but the optimal dose of nucleoside decreases by 2 orders of magnitude, indicating that these compounds are highly effective modulators of the immune response well after the initiating events have occurred. Amplification of the antibody response occurs over a wide range of antigen concentrations but is maximal at optimal antigenic concentrations. Enhancement of antibody responses in vivo is absolutely dependent upon derivatization of guanosine at C8; native guanosine is ineffective. When administered after antigen (sheep erythrocytes) to male (CBA/N X CBA/CaJ)F1 mice (which bear the xid B-cell defect) in an effort to bolster their impaired response to this T cell-dependent antigen, the brominated nucleoside induced a degree of responsiveness equivalent to that generated in the normal (female) counterparts injected with antigen and 8-bromoguanosine.

Animals↗
PubMed1983

T cell-replacing activity of C8-derivatized guanine ribonucleosides.

The capacity of the C8-substituted guanine ribonucleosides to provide T cell-like signals to cultures of splenic B cells was evaluated. We showed previously that these low m.w. nucleoside derivatives traverse the cell membrane and induce their effects from an intracellular location. The current studies clearly demonstrate that 8 mercaptoguanosine (8MGuo), when added to cultures of B cells and macrophages in the presence of antigen, is capable of supplying a "second signal" for B cells, enabling them to generate high numbers of specific plaque-forming cells against the immunizing antigen. This effect is duplicated in cultures of spleen cells from congenitally athymic mice. Inhibition of interleukin 2 (IL 2) generation by cyclosporin A, such that the antibody response of normal spleen cells is entirely abrogated, has minimal effects on the T cell-replacing activity of 8MGuo. Additivity studies with MLC supernatants as well as kinetic analyses with IL 2-associated lymphokines substantiate that these factors act by a mechanism distinct from that of 8MGuo and 8BrGuo. These observations establish these nucleoside activators as exciting new probes for T helper cell activity and an effective non-T cell source of T cell-like signals.

Animals↗
PubMed1983

Derivatized guanine nucleosides: a new class of adjuvant for in vitro antibody responses.

Guanine ribonucleosides, substituted at the C8 position with either a bromine or thiol group, are potent adjuvants when added to culture with antigen. Responses from both naive and antigen-experienced B cells are augmented by the presence of the nucleoside derivatives. Like the induction of B cell proliferation and polyclonal immunoglobulin secretion, enhancement of antibody responses is not attributable to structural analogy between 8BrGuo and the cyclic nucleotide 8Br-cGMP, because the latter compound is unable to augment the antibody response. The capacity of 8MGuo to augment both T-independent and T helper factor-supported antibody responses suggests that the nucleoside acts by directly interacting with B cells and/or antigen-presenting cells. 8MGuo retains its full adjuvant activity even when added 3 days after culture initiation, a time that is too late for freshly added T cells to support a response. Finally, supplementation of cultures of spleen cells from immunodeficient (CBA/N x CBA/CaJ)F1 male mice with the nucleoside effectively restored to normal their capacity to generate an antibody response.

Adjuvants, Immunologic↗
PubMed1983

Activation of lymphocytes by a thiol-derivatized nucleoside: characterization of cellular parameters and responsive subpopulations.

Lymphocyte activation, whether specific or nonspecific, is generally conceptualized as initiated by the binding of an activating ligand to a surface membrane receptor, followed by transduction of the signal across the cell membrane. In many situations several qualitatively distinct signals are required. We have recently described a new class of lymphocyte activator, the C8 bromine substituted guanine ribonucleosides, that traverse the cell membrane, bypassing classical triggering mechanism(s), apparently activating the lymphocyte at an intracellular site. However, the identity of the lymphocyte population(s) activated, as well as the nature of any cellular interactions involved in activation, has not been studied heretofore. The present experiments describe the cellular parameters of lymphocyte activation by a thiol substituted member of this class of activators, 8-mercaptoguanosine (8MGuo). Upon addition of this nucleoside derivative to cultures of murine spleen cells, a marked increase in [3H]TdR uptake and blast transformation ensues. Normal splenic B cells and spleen cells from congenitally athymic (nu/nu) mice are responsive to 8MGuo, whereas thymocytes and splenic T cells are not. Two subpopulations of B cells appear to be involved in the response to this nucleoside. The predominant one is a mature population that bears surface delta-chains, la antigens, C receptors, and (by indirect evidence) the Lyb3, 5, and 7 antigens. These cells also bear mu-chain and Fc receptors. In addition, a second, minor subpopulation of less mature cells that bear only mu-chain and Fc receptors also appears to be reactive to 8MGuo. The existence of this immature, reactive B cell subset was confirmed by observation of 8MGuo responsiveness in lymphocytes from 4-day-old mice whose cells do not yet exhibit these later-appearing markers. Accessory cells appear to play a minimal, if any, role in the 8MGuo response. These results establish two distinct B cell subpopulations as the major and minor cellular targets of C8-derivatized nucleosides, and suggest that the activation process results from a direct interaction between the nucleoside and target cell.

Animals↗
PubMed1983

Immunobiologic properties of the C8-derivatized guanine ribonucleosides.

In recent studies from this laboratory, the immunologic properties of a new class of activator, the C8-derivatized guanine ribonucleosides have been described. These agents are potent lymphocyte activators which appear to gain access to the interior of the cell by the purine nucleoside facilitated transport mechanism and to activate the cell at an intracellular triggering site. Cyclic GMP does not appear to be a direct or indirect mediator of these events. The major lymphocyte population responsive to these compounds appears to be a mature group of B lymphocytes with a minor contribution provided by a subpopulation of less mature B cells. These nucleoside analogues exert a variety of pleiotropic effects, including polyclonal activation of B cells to secrete immunoglobulin, immunoenhancement of thymus-dependent and thymus-independent immune responses, induction of interleukin 1-like activity in cultured macrophages, and transmission of T cell-like inductive signals to B cells. This T cell-replacing activity appears to be T cell-independent and interleukin-2 independent, but is capable of synergizing with both T cells and T cell-derived lymphokines. Moreover, the T cell-like signals provided by the C8-derivatized nucleosides appear to be independent of the first signals (leading to clonal expansion) provided by these agents, in that antigen alone is able to provide a perfectly satisfactory inductive signal for B cells. Studies to date suggest that these nucleoside derivatives are capable of ameliorating immune deficits in serveral different models of murine immunodeficiency.

Animals↗
PubMed1982

Induction of interleukin 1 secretion and enhancement of humoral immunity by binding of human C5a to macrophage surface C5a receptors.

The mechanism by which human C5a anaphylatoxin augments the primary humoral response of murine splenocytes to antigen has been investigated. Culture supernatants were generated from splenic adherent cells or macrophage cell lines after exposure to a brief pulse of human C5a. Supernatants from the macrophage-like cell line P388D1, which bears surface receptors for C5a, enhance the PFC response to antigen, whereas those from the closely related cell line P388, which lacks surface receptors for C5a, fail to cause enhancement. Supernatants from splenic adherent cells, which also bear C5a receptors, similarly augment the SRBC response. Active supernatants, but not those devoid of activity, were shown to contain interleukin 1 (IL-1) activity by both the thymocyte mitogenesis and thymocyte costimulator assays. None of the supernatants contained IL-2 activity. These observations suggest that the recently described role of human C5a as an immunopotentiating modulator is mediated by its ability to induce production of IL-1 upon binding to specific receptors at the macrophage cell surface.

Animals↗
PubMed1982

Demonstration of a specific receptor for human C5a anaphylatoxin on murine macrophages.

Human C5a anaphylatoxin is known to be a potent mediator of the acute inflammatory response. It serves to trigger a wide variety of neutrophil responses after binding to a specific cellular receptor. We have now demonstrated that this bioactive glycopolypeptide is also bound to a specific receptor found on murine resident peritoneal macrophages, thioglycollate-induced exudate macrophages, and the murine cell line P388D1. The apparent Kd of the C5a receptors. Resident macrophages appear to have an average of 2 x 10(5) binding sites per cell, whereas thioglycollate- induced cells have only 4-5 x 10(4) binding sites. The continuous cell line P388D1 is intermediate between these two cell types, exhibiting 8-10 x 10(4) C5a receptors per cell. Neither murine lymphocytes nor the parent cell line P388 displays a measurable number of C5a receptors. Macrophage receptor-C5a binding interactions are followed by cellular uptake and degradation of 125I-C5a, much as is observed with neutrophils. As demonstrated in another paper, binding of C5a to macrophages results in augmentation of the primary humoral immune response as well as enhancement of mixed lymphocyte reactions. These observations suggest that C5a should not only be considered as an acute inflammatory mediator but as an immunopotentiating modulator as well, thus serving as a critical link between complement activation and subsequent immune responses.

Animals↗
PubMed1982

The role of regulatory components from resident T lymphocytes in polyclonal B cell activation.

Resident T lymphocytes have been found to exert helper and suppressor regulatory influences with regard to polyclonal activation of murine splenic B lymphocytes elicited by lipopolysaccharide. In the normal adult spleen, only T cell helper influences are exercised over polyclonal B cell activation. This activity is a property of Lyt 1+2- T cells and does not appear to be subject to MHC restriction. Suppressive influence evidently is either latent or it exists at such a low level that its effects are difficult to detect. No regulatory activity can be recovered from the supernatants of T cells, cultured either with or without LPS. However, suppressor T cell function may be evoked by activating splenic T cells with Concanavalin A or by sonicating unstimulated splenic T cells in order to liberate a suppressive potential which is not expressed by these unstimulated cells when intact. The soluble fraction of resident splenic T cell sonicates exerts both helper and suppressor regulatory influences. The soluble helper activity is derived from Lyt l+2- T cells, whereas suppressor activity is generated from Lyt 1-2+ T cells. The suppressive activity of T cell sonicates is not restricted by the MHC gene complex. Helper and suppressor activities contained in splenic T cell sonicates were separated by gel chromatography; the suppressive activity was found to elute with a molecular weight between 68,000 and 84,000 daltons, and the helper activity eluted with a molecular weight between 15,000 and 23,000 daltons. The data indicate that helper and suppressor activities are distinct molecular entities derived from distinct splenic T lymphocyte subpopulations. The possibility that these molecules are precursors to or components of antigen-specific or nonspecific helper and suppressor factors described in the literature is discussed.

Animals↗
PubMed1982

Potentiation of the primary humoral immune response in vitro by C5a anaphylatoxin.

The effect of the anaphylatoxin C5a on the primary humoral immune response to SRBC was studied in culture of spleen cells from C3H mice. The addition of human C5a to antigen-stimulated cultures resulted in a significant, dose-dependent augmentation of the primary PFC response to antigen. The specificity of this effect was affirmed by the ability of C5ades Arg, but not of the structurally analogous C3a anaphylatoxin, to act in a parallel fashion. Enhancement could be observed over a range of doses of antigen. Brief preincubation of macrophages, but not of lymphoid cells, with C5a was sufficient to cause subsequent enhancement of the primary humoral immune responses. The duration of preincubation required for this effect closely paralleled that for binding of C5a to peritoneal cells. Immunopotentiation by C5a appears to involve the function of C5a receptor-bearing, Ia- accessory cells as well as Ia+ antigen-presenting cells. Immunopotentiation could be observed when the addition of C5a was delayed for up to 24 hr after initiation of culture. Additionally, augmentation of tritiated thymidine uptake in mixed lymphocyte reactions was enhanced by the addition of C5a in a fashion parallel to that for the primary response to SRBC. These observations support a role for C5a as a modulator of cellular immunity in addition to its role in acute inflammation. Possible cellular mechanisms and implications for immunomodulation of immune responses are discussed.

Adjuvants, Immunologic↗
PubMed1982

Modulation of the immune response by anaphylatoxin in the microenvironment of the interacting cells.

It was shown that the anaphylatoxins C3a and C5a can modulate in vitro immunological reactivities. C3a suppresses both the in vitro polyclonal antibody response and the specific antibody response to sheep red blood cells (SRBC) of both mouse spleen cells and human peripheral blood cells. The target cell in the mouse for C3a appears to be an Lyt-1+2- suppressor-inducer cell and macrophages appear not to be required. In contrast to C3a, C5a enhances in vitro responses of mice. Both the response to SRBC and the mixed lymphocyte reaction are enhanced by C5a. This enhancement appears to be through an Ia- macrophage that contains receptors for C5a. It appears that enhancement may be brought about by interleukin 1, which is released when Ia- macrophages are pulsed with C5a. It is suggested that these anaphylatoxins, when present in high concentrations in the microenvironment of the interacting cells of the immune system, play a dynamic role in the regulation of the immune response. Peptide fragments cleaved from the Fc portion of antibody, complexed with antigen in this microenvironment, may have a similar regulating role.

Animals↗
PubMed1982

Induction of immunoglobulin secretion by a simple nucleoside derivative.

8 bromoguanosine (8BrGuo), a low m.w. nucleoside derivative that rapidly traverses the lymphocyte membrane to the interior of the cell, is an extremely potent inducer of immunoglobulin production by B lymphocytes. It has recently been demonstrated that this same agent can initiate high level lymphocyte proliferation in vitro. Data in the current report demonstrate that 8Br-cGMP and other cGMP analogues are at best weak inducers of immunoglobulin secretion, being more than two orders of magnitude less effective (per molecule taken up) than 8BrGuo. Incubation of lymphocytes with 8BrGuo fails to elevate their intracellular concentrations of cGMP. Moreover, at equimolar concentrations, underivatized cGMP actually antagonized the induction of antibody production by 8BrGuo. These data, in concert with observations that many lymphocyte activators fail to alter cGMP content, that many agents that elevate cGMP fail to induce immunoglobulin synthesis, and that some cGMP-elevating agents even inhibit it, suggest that the induction of immunoglobulin production, like the induction of proliferation in B cells, is not primarily dependent upon cGMP. A simple nucleoside derivative is described, the use of which should prove to be a powerful probe for investigating the triggering mechanisms underlying the proliferative and differentiative B lymphocyte pathways at the molecular level.

Animals↗