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J G Monroe

Publications and source records attributed to J G Monroe.

At least 73 records · Page 4Linked to original sources
PubMed1988

Lymphokine regulation of inflammatory processes: interleukin-4 stimulates fibroblast proliferation.

While recent evidence from several laboratories has shown that interleukin-4 (IL-4) can act on a number of cells in addition to B lymphocytes, these have thus far been limited to cells of the hematopoietic lineage. Here we report that murine IL-4 promotes DNA synthesis in both primary and immortalized fibroblasts. Marked stimulation of [3H]thymidine incorporation was observed for primary skin fibroblasts or Balb/c3T3 cells stimulated with HPLC- or immunoaffinity-purified as well as recombinant IL-4. Responses to immunoaffinity and recombinant IL-4 were completely blocked with anti-IL-4 antibody. Similar dose/response relationships were observed for recombinant IL-4 on skin fibroblasts and an IL-4 responsive murine T cell tumor, suggesting that the receptors for this lymphokine on these cells is similar. Together, these results show that IL-4 can cause DNA synthesis by murine fibroblasts presumably through ligand-receptor interactions at the cell surface. Implications of these findings to inflammation during an immune response is discussed.

Animals↗
PubMed1988

Partial characterization of a fibroblast-stimulating factor produced by cloned murine T lymphocytes.

T cells may regulate tissue fibrosis through the elaboration of soluble factors that stimulate fibroblast growth. The authors previously identified a factor produced by cloned Schistosoma mansoni antigen-specific T cells which served as a competence factor for murine fibroblasts. In the present report, they further characterize this fibroblast-stimulating factor (FsF) and differentiate it from a number of other T-cell-derived lymphokine activities. Crude supernatants from concanavalin-activated cloned T cells were fractionated by gel filtration, ion exchange, or reversed-phase high-pressure liquid chromatography. FsF has an apparent molecular weight of 17,000 and could be differentiated from colony-stimulating factor (CSF), interleukin-3 (IL-3), and interferon (IFN) on the basis of chromatographic characteristics. Highly purified or recombinant IL-2, IL-3, CSF, and IFN had no significant effect on fibroblast proliferation. Furthermore, a monoclonal anti-B-cell-stimulating factor-1 antibody only partially blocked the fibroblast proliferation induced by T-cell supernatants.

Animals↗
PubMed1986

Ocular immune responses. II. Priming of A/J mice in the vitreous induces either enhancement of or suppression of subsequent hapten-specific DTH responses.

We previously showed that the "immunologic privilege" of the anterior chamber results not from afferent blockade, but rather from induction of hapten-specific suppressor T cells that appear after anterior chamber priming with antigen. These suppressor T cells induced by anterior chamber priming differ from those induced by i.v. priming in their ability to block the efferent as well as the afferent limb of the immune response and in their lack of idiotypic surface receptors detected by rabbit anti-idiotypic antibody. We now report that intravitreal priming with haptenated syngeneic spleen cells does not result in generation of suppressor cells, but rather, can in some instances result in an enhanced systemic immunoreactivity to the priming hapten. If soluble antigenic preparations are used, however, intravitreal priming results in the generation of the suppressor T cells, which suppress subsequent DTH and CTL responses to the immunizing hapten. The suppressor cell generation after intravitreal priming is a cyclophosphamide-sensitive process. These results demonstrate that soluble products are processed differently in ocular compartments compared with cell surface coupled ligands, and further demonstrate that the generation of hapten-specific suppressor T cells is dependent, at least in part, on the form and on the specific compartment of the eye that is inoculated.

Animals↗
PubMed1986

Anti-idiotypic treatment of BALB/c mice induces CRIa-bearing suppressor cells with altered Igh-restricted function.

The ABA-specific antibody response of A/J mice (Igh Ie) is dominated by the CRIa idiotype. In contrast, BALB/c mice (Igh Ia) do not produce CRIa-bearing anti-ABA antibodies after antigenic challenge. We have shown previously that treatment with rabbit anti-CRIa (R-anti-CRIa) induces the expression of "CRIa-like" anti-arsonate antibodies in BALB/c mice. In the present report, we demonstrate that R-anti-CRIa treatment enables BALB/c mice to respond to A/J ABA-specific first-order suppressor molecules (TsF1). Manipulated BALB/c also produced CRIa bearing ABA-specific immune response. Thus, R-anti-CRIa treatment induces a change in the characteristic Igh restriction pattern typically seen in this system. These data suggest that Igh restriction in the ABA-specific T suppressor cell pathway is the result of CRIa+ dominance in the T suppressor cell response of A/J mice. The effectiveness of idiotypic manipulation in inducing the expression of a given idiotype at both the B cell and T suppressor cell levels is discussed.

Animals↗
PubMed1986

Genetic studies on murine susceptibility to herpes simplex keratitis.

We studied the influence of lgh-linked genes on the development of keratopathy after corneal inoculation with herpes simplex virus (HSV). Using congenic strains of mice, we found that the lgh-1 gene locus, or genes closely linked to it, influence the clinical expression of HSV infection. Mice with the lgh-1e or lgh-1d allotype routinely developed severe keratopathy after HSV corneal inoculation, whereas congenic strains with lgh-1a or lgh-1b allotype were less susceptible. Cell-mediated immune responses to HSV also differed between susceptible and resistant murine strains. We interpret our results to imply a genetic influence on cell-mediated, acquired immune responses to HSV infection.

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PubMed1985

Hyper-Ia antigen expression on B cells from B6-lpr/lpr mice correlates with manifestations of the autoimmune state.

To investigate the state of activation of B cells from mice with the lpr gene defect, membrane Ia antigen (mIa) expression was analyzed on B cells from B6-lpr/lpr (lpr) and control B6- +/-/+/- mice. B cells from lpr mice exhibited marked increases in levels of mIa as determined by flow cytometry using a monoclonal anti-I-Ab,d reagent. This increase, which was progressive with age, suggests that phenotypic alteration of B-cell mIa expression is a consequence of lpr gene action. Since B-cell activation manifest by elevated mIa expression may promote productive interactions with helper T cells, these observations suggest an important role for B-cell abnormalities in the etiology of lpr-induced autoimmune disease.

Animals↗
PubMed1985

Molecular events in B cell activation. I. Signals required to stimulate G0 to G1 transition of resting B lymphocytes.

Anti-immunoglobulin antibodies (anti-Ig) can stimulate a majority of resting B cells via their receptor Ig. Evidence suggests that the signals generated after this ligand-receptor interaction may be transduced via hydrolysis of inositol phospholipids. In other systems, the ability of inositol phospholipid hydrolysis to link receptor-ligand interactions to subsequent activational events has been suggested to relate to the ability of metabolic intermediates of this hydrolytic process to facilitate activation of protein kinase C and mobilization of Ca+2. In this study, we investigated the importance of protein kinase C and Ca+2 mobilization in the signaling mechanism by which anti-Ig drives B cells to undergo G0 to G1 transition. Our results show that pharmacologic inhibition of either protein kinase C activity or channel-mediated Ca+2 influx completely abrogates the increase in RNA synthesis associated with B cell activation after stimulation by anti-Ig. This suggests that pathways leading to both protein kinase C activation and elevation of intracellular Ca+2 are critical for receptor Ig-mediated G0 to G1 transition. Furthermore, studies in which anti-Ig-induced signaling could be bypassed by directly facilitating Ca+2 mobilization and protein kinase C activation using Ca+2 ionophore and phorbol diester show that these events are sufficient to drive the majority of resting B cells into G1 in the absence of additional signaling from accessory cells or extra-cellular factors. However, like anti-Ig-induced stimulation, Ca+2 ionophore and phorbol diester are relatively inefficient in driving B cells that have entered G1 into S phase. We discuss the relevance of these results towards the transduction mechanism linking B cell membrane-associated Ig-generated signals with subsequent activation events.

Animals↗
PubMed1985

Genetic and biological characterization of a T suppressor cell induced by anti-idiotypic antibody.

The cellular and molecular characteristics of anti-idiotype-induced suppression have been investigated. We have shown that i.v. immunization of A/J or C.AL-20 mice with rabbit antibodies against the major cross-reactive idiotype on A/J anti-ABA antibodies induces splenic suppressor T cells (Ts) able to suppress T cell-mediated cytolytic and delayed-type hypersensitivity responses to ABA. In these studies, we compare the T suppressor activity manifested by anti-Id-induced suppressor cells with that described previously after conventional antigen priming. Results indicate that i.v. injection of anti-idiotypic antibodies primes for efferent level Ts; in contrast, i.v. administration of ABA-coupled cells induces afferent level suppressor cells. Soluble cell lysates, containing suppressor factor(s) derived from these anti-idiotype-induced Ts, can also mediate suppression of T cell immune responses in an efferent manner. Factor-mediated suppression is MHC-unrestricted and is also observed in mice pretreated with cyclophosphamide, suggesting that this activity is analogous to third-order suppression. Furthermore, this factor suppresses the T cell-mediated DTH and CTL responses in an antigen-nonspecific but Igh-restricted manner. These latter results suggest that the cellular elements conferring antigen specificity and Igh restriction are separate. The implications of these findings to the relationship between idiotypic elements, antigen-binding structures, and Igh restriction elements on immunoregulatory T cells are discussed.

Animals↗
PubMed1984

B cell activation. IV. Induction of cell membrane depolarization and hyper-I-A expression by phorbol diesters suggests a role for protein kinase C in murine B lymphocyte activation.

Analysis of the effects of phorbol diesters on mouse B lymphocyte kinase C activity, membrane potential, mI-A expression, and cell cycle state are reported. Results indicate that the phorbol diesters PMA and 4 beta-PDD, which are potent tumor promoters, activate partially purified B cell protein kinase C and stimulate B cell membrane depolarization and increased mI-A expression. The analog 4 alpha-PDD has none of these effects. Similarly, none of the phorbol diesters tested promoted G0 to G1 transition of B lymphocytes. Results are consistent with the possibility that the transmembrane signal transduction mediated by cell membrane immunoglobulin, which results in membrane depolarization and increased I-A antigen expression, operates via activation of protein kinase C.

Animals↗
PubMed1984

B cell activation. V. Differentiation signaling of B cell membrane depolarization, increased I-A expression, G0 to G1 transition, and thymidine uptake by anti-IgM and anti-IgD antibodies.

Although studies have suggested that B cell membrane-associated IgM and IgD may function differently in the generation of humoral immune responses, this difference has proven difficult to define precisely. Toward a better understanding of the function of these antigen receptors, we compared the ability of F(ab')2 fragments of antibodies specific for mouse Fab, IgM, and IgD to induce early changes in B cell physiology that are indicative of cell activation. Specifically, we assessed the ability of membrane IgM (mIgM) or membrane IgD (mIgD) or both in combination to transduce signals that result in membrane depolarization, increased I-A expression, G0 to G1 transition, and thymidine uptake. Results indicate that at low levels of anti-receptor antibody (0.01 to 0.1 microgram/ml) both isotypes transduce signals for the induction of membrane depolarization and increased I-A expression by a significant proportion of B cells, i.e., Ig+ cells. Higher concentrations of ligand (5 to 25 micrograms/ml) are required to induce a significant proportion of cells to undergo G0 to G1 transition and increase thymidine uptake. At optimal concentrations, anti-IgM and anti-IgD induce membrane depolarization and increased I-A expression by 80 to 90% of B cells. Although mIgM also transduces signals sufficient for G0 to G1 transition by 80 to 90% of B cells, mIgD transduces signals sufficient for G0 to G1 by only about 40% of B cells. A similar difference exists for the induction of thymidine uptake. Thus, results suggest that membrane Ig may transduce two different signals depending upon the amount of ligand that they bind. Although in some B cells mIgD can transduce both signals resulting in membrane depolarization and progression into G1, in most cells mIgD transduces only the first signal, resulting in membrane depolarization and increased I-A expression.

Animals↗
PubMed1983

B cell activation. III. B cell plasma membrane depolarization and hyper-Ia antigen expression induced by receptor immunoglobulin cross-linking are coupled.

We report investigation of the relationship between ligand-induced B cell plasma membrane depolarization and increased expression of membrane-associated, I-A subregion encoded (mI-A) antigens. Results demonstrate that equal frequencies of B cells are stimulated to undergo membrane depolarization and to increase mI-A expression in response to mitogen, anti-Ig, and thymus-independent (TI) or thymus-dependent (TD) antigens. Further, a cause-and-effect relationship between these two events is suggested by results that demonstrate that inhibition of anti-Fab--induced depolarization by valinomycin also inhibits the subsequent increase in mI-A antigen expression and "passive" (non-ligand-mediated) depolarization of murine B cells by K+ results in hyper-mI-A antigen expression. Based upon these results we hypothesize that antigen-mediated receptor cross-linking results in signal transduction via membrane depolarization, which is resultant in increased mI-A antigen synthesis and cell surface expression. This increase in mI-A antigen density may render the B cell more receptive to subsequent interaction with I-region-restricted helper T cells.

Animals↗
PubMed1983

Sorting of B lymphoblasts based upon cell diameter provides cell populations enriched in different stages of cell cycle.

Here we report analysis and correlation of changes in cell size and cycle state resulting from exposure of murine B lymphocytes to the mitogens lipopolysaccharide (LPS) and dextran sulfate (DxSO4). Cell cycle changes are assessed by flow cytofluorometric analysis of acridine orange stained cells. Cell diameters are determined by flow cytometric analysis of the pulse-width (time of flight) of the axial light extinction signal. Results indicate that within 12 h of exposure of B cell populations to these mitogens, cells displaying increased diameter and containing increased RNA can be detected. Under these conditions, increased RNA content is considered indicative of G0 to G1 transition or entry into cell cycle (Darzynkiewicz et al., 1976). Progressive increases in cell size and transition through G1, S, G2, and M occur in parallel during 48 h of culture with mitogens. Sorting of cells based upon size followed by cell cycle analysis reveals a direct correlation between cell size and cycle phase. Specifically, cells 4.5-5.5 microns in diameter are in primarily G0. Cells 5.5-7.0 microns in diameter are in early G1. Populations of cells 7.0-10 microns in diameter are comprised of late G1 and S phase cells. Populations of cells 10-12 microns in diameter consist of S, G2, and M phase cells. The importance of this correlation is discussed in view of needs to more rigorously define B cell populations for investigations of biochemical events of and accessory cell requirements for activation of B lymphocytes.

Acridine Orange↗
PubMed1983

B cell activation. I. Anti-immunoglobulin-induced receptor cross-linking results in a decrease in the plasma membrane potential of murine B lymphocytes.

We report analyses of the effect of anti-Fab antibodies on plasma membrane potential of mouse B lymphocytes. Results indicate that divalent fragments of anti-Fab antibodies mitogenic for B cells stimulate membrane depolarization detectable by cytofluorometric analysis of 3,3'-dipentyloxacarbocyanine iodide-stained cells. Depolarization is detectable within 5 min of exposure to ligand and maximal within 1 h of exposure when greater than or equal to 80% of splenic B cells exhibit decreased membrane potential. The ineffectiveness of monovalent Fab antibody fragments in inducing this event suggests that receptor immunoglobulin cross-linking is essential. Frequencies of cells induced to enter cell cycle, as assessed by acridine orange cell cycle analysis, are equal to those induced to depolarize by lipopolysaccharide plus dextran sulfate or anti-Fab, which suggests a relationship between these events. However, membrane depolarization is itself an insufficient signal to promote subsequent thymidine uptake, as evidenced by the fact that doses of anti-Fab that are suboptimal for thymidine uptake induce maximal depolarization. These results suggest that cross-linking of surface immunoglobulin on B cells may provide an initial signal for activation but is itself insufficient to drive B cell proliferation.

Animals↗
PubMed1983

B lymphocyte activation: entry into cell cycle is accompanied by decreased expression of IgD but not IgM.

To gain insight into the function of cell surface IgM (sIgM) and IgD (sIgD), the expression of these markers on B lymphocytes was quantitated during activation and progression through the cell cycle. Specifically, analysis and correlation of changes in cell cycle state, sIgM and sIgD expression and cell size following exposure of murine B cells to mitogenic levels of lipopolysaccharide and dextran sulfate is reported. As assessed by flow cytometric acridine orange analysis, a large proportion of normal splenic B cells respond within 48 h of exposure to these mitogens by entry into the cell cycle. This response is accompanied by an increase in cell size as determined by flow cytometric "time of flight" measurement. Flow cytometric immunofluorescence analysis reveals a simultaneous alteration in sIg expression. Specifically, cells leaving G0 and transiting G1 increase in diameter from 5 microns to 6 microns and lose greater than 80% of sIgD while sIgM remains constant. Progression through the remainder of the cell cycle is accompanied by a further increase in mean cell diameter to approximately 12 microns while sIgM and sIgD levels remain at G1 levels. The abrupt loss of sIgD as cells transit G1 suggests that an active process mediates this decrease.

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