Search PubMed⌕ Search

Biomedical subjects

E G Engleman

Publications and source records attributed to E G Engleman.

At least 145 records · Page 8Linked to original sources
PubMed1984

Suppression of pokeweed mitogen-stimulated immunoglobulin production in patients with rheumatoid arthritis after treatment with total lymphoid irradiation.

Patients with intractable rheumatoid arthritis (RA) were treated with total lymphoid irradiation (TLI, 2000 rad). We previously reported long-lasting clinical improvement in this group associated with a persistent decrease in circulating Leu-3 (helper subset) T cells and marked impairment of in vitro lymphocyte function. In the present experiments, we studied the mechanisms underlying the decrease in pokeweed mitogen stimulated immunoglobulin (Ig) secretion observed after TLI. Peripheral blood mononuclear cells (PBL) from TLI-treated patients produced 10-fold less Ig (both IgM and IgG) in response to pokeweed mitogen than before radiotherapy. This decrease in Ig production was associated with the presence of suppressor cells in co-culture studies. By using responder cells obtained from normal individuals (allogeneic system), PBL from eight of 12 patients after TLI suppressed Ig synthesis by more than 50%. In contrast, PBL from the same patients before TLI failed to suppress Ig synthesis. Suppression by post-TLI PBL was also demonstrated in an autologous system by using responder cells cryopreserved before TLI. Again, only cells obtained after TLI were suppressive in four of seven patients. PBL with suppressive activity contained suppressor T cells, and the latter cells bore the Leu-2 surface antigen. In 50% of the patients studied, suppressor cells were also found in the non-T fraction and were adherent to plastic. Interestingly, the Leu-2+ cells from TLI-treated patients were no more potent on a cell per cell basis than purified Leu-2+ cells obtained before TLI. Additional experiments suggested that the suppression mediated by T cells after TLI is related to the increased ratio of Leu-2 to Leu-3 cells observed after radiotherapy.

Animals↗
PubMed1983

Immunoregulatory T cell circuits in man. Alloantigen-primed inducer T cells activate alloantigen-specific suppressor T cells in the absence of the initial antigenic stimulus.

Although alloantigen-specific suppressor T cells are generated in MLR, the cellular signals that lead to activation of suppressor T cells as opposed to cytotoxic T cells are unknown. The current study was undertaken to characterize interactions among T cell subsets involved in the generation of suppressor T cells in MLR. Human peripheral blood Leu-2+ (suppressor/cytotoxic) and Leu-3+ (helper/inducer) T cell subsets were activated with allogeneic non-T cells and then examined for their inductive effects on fresh autologous T cells. Fresh Leu-2+ cells proliferated in response to alloantigen-primed Leu-3+ cells and subsequently suppressed the response of fresh autologous Leu-3+ cells to the original, but not third party, allogeneic stimulator non-T cells. Moreover, only Leu-2+ cells that lacked the 9.3 marker, an antigen present on the majority of T cells including precursors of cytotoxic T cells, differentiated into suppressor cells. The alloantigen-specific suppressive effect of Leu-2+,9.3-cells was not mediated by cytolysis of allogeneic stimulator cells, nor could it be explained by alteration of MLR kinetics. Suppression was observed only when activated Leu-2+ cells were added to fresh MLRs within 24 h of initiation of cultures, suggesting that these cells block an early phase of the activation of Leu-3+ cells in MLR. These results indicate that alloantigen-primed inducer T cells can activate alloantigen-specific suppressor T cells in the absence of allogeneic stimulator cells.

Cell Division↗
PubMed1983

Sustained improvement of intractable rheumatoid arthritis after total lymphoid irradiation.

Total lymphoid irradiation (TLI) was administered to 11 patients who had intractable rheumatoid arthritis that was unresponsive to conventional medical therapy, including aspirin, multiple nonsteroidal antiinflammatory drugs, gold salts, and D-penicillamine. Total lymphoid irradiation was given as an alternative to cytotoxic drugs such as azathioprine and cyclophosphamide. After radiotherapy, 9 of the 11 patients showed a marked improvement in clinical disease activity as measured by morning stiffness, joint tenderness, joint swelling, and overall functional abilities. The mean improvement of disease activity in all patients ranged from 40-70 percent and has persisted throughout a 13-28 month followup period. This improvement permitted the mean daily steroid dose to be reduced by 54%. Complications included severe fatigue and other constitutional symptoms during radiotherapy, development of Felty's syndrome in 1 patient, and an exacerbation of rheumatoid lung disease in another. After therapy, all patients exhibited a profound T lymphocytopenia, and a reversal in their T suppressor/cytotoxic cell to helper cell ratio. The proliferative responses of peripheral blood mononuclear cells to phytohemagglutinin, concanavalin A, and allogeneic leukocytes (mixed leukocyte reaction) were markedly reduced, as was in vitro immunoglobulin synthesis after stimulation with pokeweed mitogen. Alterations in T cell numbers and function persisted during the entire followup period, except that the mixed leukocyte reaction showed a tendency to return to normal values.

Adult↗
PubMed1983

Changes in T-cell subsets in patients with rheumatoid arthritis treated with total lymphoid irradiation.

Patients with intractable rheumatoid arthritis (RA) were treated with total lymphoid irradiation (TLI, 2000 rads). We previously reported long-lasting clinical improvement associated with marked suppression of in vitro lymphocyte function in this group. In an attempt to better understand the mechanism of immunosuppression and clinical changes observed after TLI, we studied in greater detail changes in peripheral blood T-cell subsets identified by monoclonal antibodies. Before TLI, RA patients had a higher percentage of Leu-3 (helper subset) cells and a lower percentage of Leu-2 (suppressor/cytotoxic subset) cells than normals. Immediately after TLI, the absolute numbers of both Leu-2 and Leu-3 cells were reduced by at least 90%. Within 6-12 weeks, the number of Leu-2 cells returned to the pretreatment levels, but the levels of Leu-3 cells remained depressed for months thereafter. The lack of repopulation of Leu-3 cells resulted in a marked increase in the ratio of Leu-2 to Leu-3 cells as compared to pretreatment values (1.73 +/- 0.23 vs 0.39 +/- 0.06), and in a decrease in the percentage and absolute number of total T (Leu-1 and Leu-4) cells. The failure of Leu-3 cells (which mediate predominantly helper/inducer functions) to repopulate the peripheral blood may contribute to the prolonged clinical immunosuppression observed after TLI. Similar changes in T-cell subsets were not observed in RA patients given remittive drugs or low doses (200 rads) of radiotherapy. Thus, TLI differs from other treatment modalities with regard to its prolonged selective effect on the Leu-3 subset.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1983

A simplified new method for HLA-DR typing using the TM1 monoclonal antibody.

A new modification of an HLA-DR typing technique is described which makes DR typing as rapid and simple as routine HLA-A,B,C typing. In this new method, designated the TM1 technique, carboxyfluoresceindiacetate labeled peripheral blood lymphocytes are added directly to DR typing trays. The T cells are then lysed by addition of TM1, a pan-T cytotoxic IgM monoclonal antibody, and residual B-cell reactivity with cytotoxic DR alloantibodies is read as in routine fluorochromasia microlymphocytotoxicity. HLA-DR typing by the TM1 technique compares favorably to typing by methods using B cells enriched by sheep red blood cell rosetting or by Degalan bead columns. The TM1 technique also works well with cells that have been cryopreserved as well as with cells that have been separated from whole blood drawn as much as 3 days earlier. Finally, because TM1 is so effective in lysing normal T lymphocytes, this antibody may prove useful in functional in vitro and in vivo studies requiring T-cell depletion.

Antibodies, Monoclonal↗
PubMed1983

Hodgkin's disease susceptibility: linkage to the HLA locus demonstrated by a new concordance method.

The role of genetic susceptibility in the pathogenesis of Hodgkin's Disease has been considered relatively minor because of the rarity of familial disease, the absence of an identified pattern of inheritance, and the weakness of HLA associations in population studies. The availability of four prospectively ascertained HD families permitted reappraisal of the cosegregation of HLA and HD susceptibility by a new extended concordance analysis method. HLA haplotype concordance among patients was greater than that expected by chance alone for our four families (P less than 0.022) and also for these in combination with twelve informative families in the literature (P less than 0.0015). This study thus provides a new method, based on genotype concordance of affected relatives, for assessing linkage of HLA and disease susceptibility, and new evidence for the genetic control of susceptibility to HD. The model presented, as well as alternative and more complex models, points to the existence of an HD susceptibility gene in or near the HLA region, which, in the presence of a suitable etiologic agent or additional genetic susceptibility, leads to the induction of HD.

Adult↗
PubMed1983

Inhibition of a Langerhans cell-mediated immune response by treatment modalities useful in psoriasis.

Neither the pathogenesis of psoriasis nor the mechanism whereby seemingly diverse therapies alter the disease is understood. In this study, several antipsoriatic agents were tested for their effects on the skin cell lymphocyte reaction (SLR), an immunologic assay in which HLA-DR antigens on Langerhans cells (LC) stimulate proliferation of allogeneic lymphocytes. Every agent tested (cortisol, methotrexate, hyperthermia, anthralin) inhibited the SLR at therapeutic dose levels. By contrast, a variety of antibiotics, an anti-inflammatory agent, and lithium carbonate and propranolol, two drugs known to be ineffective in psoriasis, failed to inhibit the SLR. Finally, we have shown that hyperthermia and anthralin treatments are toxic for LC whereas they have little or no effect on keratinocyte viability. These results suggest that antipsoriatic agents may act in psoriasis by alteration or killing of LC.

Anthralin↗
PubMed1983

Selective enrichment of human epidermal cell subpopulations using monoclonal antibodies.

In studying the mechanisms that regulate the growth and differentiation of the human epidermis, it would be helpful to obtain relatively pure populations of the different epidermal cell types. We have used a solid-phase immunoabsorption method termed "panning" to positively select two types of epidermal cells: Langerhans cells and the keratinocytes found in the basal cell layer (basal cells). To attach basal cells to a goat anti-mouse IgG-coated plastic surface, we used murine monoclonal antibodies (VM-1 or VM-2), which were recently produced in our laboratory and bind specifically to antigens on human basal cells. Using antibodies VM-1 or VM-2, we panned for basal cells and obtained a yield of about 40 percent (an enrichment of about 2.5-fold). The cells enriched for basal cells demonstrated much better growth and DNA synthesis than did the cell fraction depleted of basal cells. For positive selection of Langerhans cells, we used OKT6, a murine monoclonal antibody that binds specifically to Langerhans cells in the epidermis. We determined that of those cells preincubated with OKT6 and adherent to an antibody-coated petri dish surface, about 70 percent demonstrated OKT6 binding by fluorescence microscopy. This represents a 15- to 20-fold enrichment for Langerhans cells. The nonadherent cell fraction contained less than 1 percent OKT6-positive cells. Ultrastructural studies showed that the cells thus separated were Langerhans cells. The OKT6-positive but not the OKT6-negative cells were capable of stimulating allogeneic lymphocytes in the skin-cell-lymphocyte reaction. Thus the panning technique is an effective method for obtaining greatly enriched subpopulations of viable epidermal cells.

Animals↗
PubMed1983

Activation of antigen-specific suppressor T cells in the presence of cyclosporin requires interactions between T cells of inducer and suppressor lineage.

To probe the mechanism of suppressor T cell generation in man, we have carried out mixed leukocyte reactions (MLR) in the presence of cyclosporin (CsA), a fungal metabolite which prevents the generation of cytotoxic lymphocytes while permitting activation of suppressor cells. After a 12-d MLR in the presence of 1 microgram/ml CsA, T cells were fractionated into subsets with monoclonal antibodies, and each subset was tested for the ability to inhibit a second fresh MLR that is devoid of CsA. The results show that Leu 2+ T cells derived from the first culture suppress the second MLR in an HLA-DR antigen-specific manner and in the absence of detectable lysis of stimulator cells. However, Leu 2+ cells do not develop into suppressor cells unless acted upon by alloantigen-primed Leu 3+ inducer cells. Furthermore, only those Leu 3+ cells that also express the Leu 8 marker (Leu 3+, 8+) are capable of inducing suppressor cells. Thus, antigen-specific feedback inhibition of an immune response in man results from an ordered series of interactions between T cells of distinct phenotype.

Antibodies, Monoclonal↗
PubMed1983

The regulation of antibody secreting cells generated in the autologous mixed leukocyte reaction in man.

Although the autologous mixed leukocyte reaction (AMLR) is usually defined as a proliferative response of T cells to autologous non-T cells, the reaction also results in the synthesis of immunoglobulin (Ig) by B cells. The induction of Ig synthesis has an absolute requirement for helper (Leu 3+) T cells, whereas suppressor (Leu 2+) cells inhibit the response. To assess the immunoregulatory potential of T cells activated in this reaction, 8 day cultures between T and autologous non-T cells were carried out, after which the activated T cells were fractionated into subsets with monoclonal antibodies to T cell markers and HLA-DR antigen. Each population was cocultured in fresh AMLR, and on the 8th day of culture, Ig secreting cells were measured in a reverse hemolytic plaque assay. The results show that activated Leu 2+ DR+ T cells were at least 50 times more potent as suppressors of IgM and IgG synthesis than fresh Leu 2+ cells alone. The activation of this Leu 2+ DR+ subpopulation required Leu 3+ cells in the primary culture. Furthermore, in the absence of fresh Leu 2+ cells in the second culture, little or no suppression was observed, suggesting that the Leu 2+ DR+ cells act to amplify or induce suppressor effects of fresh Leu 2+ cells. The possibility that suppressor-amplifier and suppressor-effector cells are derived from phenotypically distinct resting cells was supported by additional experiments utilizing a monoclonal antibody (anti-Leu 8) that subdivides resting Leu 2 cells. Thus, neither Leu 2+ 8+ nor Leu 2+ 8- cells alone suppress Leu 3+ induced immunoglobulin synthesis, but in combination the subsets are markedly inhibitory. These results indicate that at least two distinct subpopulations of Leu 2+ cells are required for maximal suppression of an immune response, and that immunoregulatory circuits analogous to those described in mice exist in man. Future studies will be directed at determining whether selected defects in the suppressor-amplifier circuit occur in diseases characterized by disordered immunoregulation.

Antibodies, Monoclonal↗
PubMed1983

Alloantigen-specific cytotoxic and suppressor T lymphocytes are derived from phenotypically distinct precursors.

Although Leu-2+ (OKT8+) T cells activated in the mixed lymphocyte reaction (MLR) mediate both alloantigen-specific cytotoxicity and suppression of alloantigen-induced proliferation, it is not known whether these functions derive from a single cell type or phenotypically distinct cells. This study was undertaken to examine the alloantigen-specific cytolytic and suppressor potential of two subpopulations of Leu-2+ cells distinguishable from one another on the basis of their binding to the monoclonal antibody 9.3. Leu-2+, 9.3+ and Leu-2+, 9.3- populations were purified from peripheral blood, cultured for 7 days with autologous helper/inducer (Leu-3+) cells and allogeneic non-T cells, and reisolated before testing for cytotoxicity and suppression. All detectable alloantigen-specific cytolytic activity was confined to the Leu-2+, 9.3+ subpopulation. Killing by this subset was specific for the HLA-A and B (class I) major histocompatibility complex (MHC) antigens of the priming cell. By contrast, suppression of proliferation was mediated predominantly by the Leu-2+, 9.3- cells, and suppression by this subpopulation was specific for the HLA-DR (class II) MHC antigens of the priming cell. The development of suppression by Leu-2+, 9.3- cells was unaffected by cyclosporin A (CsA), an agent shown previously to block the development of cytolytic but not suppressor cells in MLR. Alloactivated Leu-2+, 9.3+ cells were slightly inhibitory of fresh MLR, but this effect as well as the development of cytolytic cells was completely abrogated by CsA. These results indicate that suppressor and cytolytic Leu-2+ T cells activated in MLR are derived from distinct precursors separable by antibody 9.3.

Animals↗
PubMed1983

Human T lymphocyte proliferation induced by a pan-T monoclonal antibody (anti-Leu 4): heterogeneity of response is a function of monocytes.

Anti-Leu-4 is a murine monoclonal antibody that defines a molecule of 20,000 to 25,000 daltons present on all mature T lymphocytes in man. When cultured in the presence of 10 to 1000 ng/ml anti-Leu-4, the T cells of most individuals proliferate with peak responses on the third day of culture. T cells of both helper and suppressor lineages proliferate, but only in the presence of monocytes. Approximately 40% of individuals tested responded weakly or not at all to anti-Leu-4, despite normal responses to other stimuli. The variation in responsiveness between individuals could not be explained by differences in Leu-4 antigen density on the surface of T cells, differences in the rate of Leu-4 antigen modulation, or structural differences in the Leu-4 molecule as defined by the method of two-dimensional polyacrylamide gel electrophoresis. In the presence of monocytes from high responders, the T cells from low responders proliferated vigorously to anti-Leu-4, whereas monocytes from low responders failed to support proliferation by high responder T cells. On the other hand, low responder monocytes did not prevent T cells from proliferating in the presence of high responder monocytes. These results suggest that the failure of some individuals to respond to anti-Leu-4 is due to the absence or dysfunction of an essential monocyte population.

Adult↗
PubMed1983

Analysis of HLA-B27 antigen with monoclonal antibodies.

To explore the possibility that the HLA-B27 antigen may exist in more than one form, murine monoclonal antibodies were produced to B27 molecules. The first such antibody, anti-B27M1, reacts with 100% of B27 + cells and, therefore, does not distinguish B27 + healthy individuals from those with spondyloarthropathies. A second antibody, anti-B27M2, recognizes a variant of the B27 molecule that is present in most but not all Caucasian B27 + individuals. The frequency of B27M2(+) variants also appears to differ among different ethnic groups. Preliminary studies suggest that B27 + patients with ankylosing spondylitis are less likely than B27 + healthy individuals to express the B27M2 variant.

Animals↗
PubMed1983

Immunochemical variants of HLA-B27.

Detailed study of HLA-B27 was prompted by the extremely strong associations between this antigen and spondyloarthropathies. Despite the relative homogeneity of this antigen when defined by alloantisera, B27 reactivity with the monoclonal antibody B27M2 suggests previously unrecognized heterogeneity. To define and confirm this heterogeneity on a molecular level, detergent extracts were prepared from B cell lines derived from individuals reactive (+) or unreactive (-) with the B27M2 antibody. Extracts were immunoprecipitated by specific allogeneic or monoclonal antibodies and analyzed by two-dimensional polyacrylamide gel electrophoresis. By this method the B27M2+ and B27M2- variants of HLA-B27 had different isoelectric points (pl) and could be distinguished from each other and from a different (Bw44) control alloantigen. Blockade of glycosylation by pretreatment of cells with tunicamycin did not alter pl but did reduce HLA antigens by approximately 3000 daltons. These data demonstrate that B27 antigens can be subdivided into subsets with different molecular composition. The effects of this heterogeneity upon the associations of B27 and disease are not yet known.

Animals↗
PubMed1983

Blocking of human T lymphocyte functions by anti-Leu-2 and anti-Leu-3 antibodies: differential inhibition of proliferation and suppression.

We have shown previously that monoclonal antibodies to the Leu-2 and Leu-3 T cell antigens block the response of their respective subsets in allogeneic MLR. The present study was an effort to explore the mechanism of inhibition and to determine if anti-Leu-2 and anti-Leu-3 antibodies affect the responses to stimuli in addition to alloantigens. Our results indicate that antibodies to Leu-2 and Leu-3 have profound inhibitory effects on proliferation by their respective T cell subsets responding to a variety of stimuli, including specific soluble antigens and alloantigen. This effect was characterized by the following features: a) For optimal inhibition of proliferation, antibody must be present at the onset of antigenic stimulation. b) Inhibition is augmented by increasing the concentration of antibody or decreasing the concentration of antigen. c) Fab fragments of both anti-Leu-2a and anti-Leu-3a antibodies also block proliferation. In addition to their effects on T cell proliferation, anti-Leu-3 antibody blocked T cell-dependent lg synthesis induced in MLR, and anti-Leu-2 antibody prevented the induction, in vitro, of Leu-2+3- suppressor cells of lg synthesis. Taken together, these results suggest that antibodies to antigenic determinants on the Leu-2 and Leu-3 molecules competitively block segments of these structures that bind to alloantigen or nominal antigen. On the other hand, anti-Leu-2a antibody failed to block suppression of the MLR by in vivo activated, antigen-specific Leu-2+3- suppressor cells, which suggests that the Leu-2a epitope does not transmit antigen-specific signals from these differentiated suppressor T cells.

Animals↗
PubMed1982

Immunoglobulin secretion in the human autologous mixed leukocyte reaction. Definition of a suppressor-amplifier circuit using monoclonal antibodies.

The induction of immunoglobulin (Ig) synthesis in the autologous MLR has an absolute requirement for helper/inducer (Leu-3) T cells, whereas an excess of suppressor/cytotoxic (leu-2) cells suppresses the response. The current study was an effort to assess the immunoregulatory potential to T cells activated in the autologous mixed-leukocyte response (MLR). T cells were cultured with autologous non-T cells for 8-9 d, after which the activated T cells were fractionated into subsets with monoclonal antibodies to T cell markers and HLA-DR antigen. Each population was co-cultured in fresh autologous MLR, and on the 8th day of culture, Ig-secreting cells were measured in a reverse hemolytic plaque assay. The results show that activated Leu-2, DR+ T cells, but neither Leu-2, DR- nor Leu-3 T cells, were at least 50 times more potent as suppressors of IgM and IgG synthesis than fresh Leu-2 cells alone. The activation of this Leu-2, DR+ subpopulation required Leu-3 cells in the primary culture. Furthermore, in the absence of Leu-2 cells in the second culture, little or no suppression was observed, suggesting that the Leu-2, DR+ cells act to amplify or induce suppressor effects of fresh Leu-2 cells. This indicates that at least two distinct subpopulations of Leu-2 cells are required for maximal suppression of an immune response, and that immunoregulatory circuits analogous to those described in the mouse exist in man.

Antibodies, Monoclonal↗