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Biomedical subjects

G Hedlund

Publications and source records attributed to G Hedlund.

108 records · Page 6Linked to original sources
PubMed1988

Two subsets of human CD4+ T helper cells differing in kinetics and capacities to produce interleukin 2 and interferon-gamma can be defined by the Leu-18 and UCHL1 monoclonal antibodies.

Human CD4+ T helper cells were separated into CD4+45R+ and CD4+45R- cells. When stimulated with the polyclonal activator staphylococcal enterotoxin A in the presence of autologous monocytes, these two subsets exhibited a striking difference in production of interleukin 2 (IL2) and interferon-gamma (IFN-gamma). While the CD4+45R- subset produced maximal amounts of IL2 within 24 h and IFN-gamma within 72 h, the CD4+45R+ subset produced no IL2 within 24 h and merely marginal amounts of IFN-gamma as assayed after 24 to 96 h. This discrepancy between the subsets was found when the cells were stimulated by other accessory cell-dependent activators and by the accessory-independent combination of the calcium ionophore A23187 and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate as well. The inability of the CD4+45R+ cells to produce IL2 during the first day of culture was not due to any modulation of either the CD4 or the CD45R antigens, as purified CD4+45R+ cells obtained by negative panning selection with the reciprocal UCHL1 monoclonal antibody responded in a similar manner as the positively selected sorted CD4+45R+ cells. Analysis of the kinetics of IL2 production by the two T helper cell subsets clearly demonstrated that the IL2 recorded after 1 day of culture was entirely produced by the CD4+45R- cells, whereas the CD4+45R+ cells produced IL2 during and after the second day of culture. This discrepancy in kinetics was not due to an increased absorption of IL2 by the CD4+45R+ cells during the first day of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1988

Inhibitory effects of histamine on interleukin 2 and gamma interferon production of different human T helper cell subsets.

We have previously demonstrated that histamine can inhibit human helper T cells by direct interaction with these cells. It has now been investigated whether histamine inhibits lymphokine production by various subsets of CD4+ human T cells separated with the Leu-8 (p80) and Leu-18 (anti-CD45R;p220) monoclonal antibodies (MoAb). Histamine was shown to suppress to a similar extent the production of interleukin 2 (IL-2) and gamma interferon (IFN-gamma) by Leu 3+, Leu 3+8+, and Leu 3+8- cell subsets. Mitogen-activated, unseparated Leu 3+ and purified Leu 3+8- cells produced maximal amounts of IL-2 after 24 h and IFN-gamma after 72 h of culture. In contrast, the Leu 3+18+ subset produced no IL-2 after 24 h, and maximal amounts of IL-2 no sooner than 48 h of culture, and only small amounts of IFN-gamma during the entire culture period of 96 h. Histamine suppressed the production of IL-2 by both subsets, both when produced early (after 24 h), as in the case of the Leu 3+18- subset, and late (after 48 h of culture), as for the Leu 3+18+ subset. The IFN-gamma production by the Leu 3+ and Leu 3+18- cells and the marginal production by Leu 3+18+ cells were significantly suppressed by histamine. Dual staining with Leu 8 and Leu 18 MoAb demonstrated that the Leu 18- cell compartment included both Leu 8+ and Leu 8- cells. It was shown that the inhibitory effect of histamine on the early production of IL-2 and the major production of IFN-gamma by T helper cells is mediated via action on both the Leu 3+18-8- and the Leu 3+18-8+ cells. The inhibitory effect of histamine on the late production of IL-2 is mediated mainly via action on Leu-18+ cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Lymphocyte subpopulations and lymphokine production in children with constitutional aplastic anemia.

The expression of lymphocyte surface markers as well as the production of interleukin-2 (IL-2) and interferon-gamma (IFN) by mitogen-stimulated peripheral blood mononuclear cells (MNC) have been studied in five children with constitutional aplastic anemia. A significantly reduced T4/T8 ratio was found and two of five patients also had a reduced percentage of B cells. One patient had a high percentage of HLA-DR positive T8+ cells, very suggestive of a high degree of circulating activated T suppressor/cytotoxic cells. IL-2 production was reduced in two patients, whereas IFN production was only reduced in one of these. The abnormalities found correlate with the duration of the bone marrow failure. The patients with the longest duration of bone marrow failure also exhibited the lowest T4/T8 ratio. No spontaneous IFN production was detected in any of the patients. There was no clinical benefit or reversal of the immune abnormalities during and following treatment with cimetidine and cyclosporine A in two patients.

Anemia, Aplastic↗
PubMed1987

Analysis of the murine lymphokine-activated killer (LAK) cell phenomenon: dissection of effectors and progenitors into NK- and T-like cells.

Murine as well as human lymphokine-activated killer (LAK) cells have been reported to have several characteristics of T lymphocytes and to be clearly distinct from natural killer (NK) cells. The present study of murine LAK cells showed that cytotoxic cells generated in the presence of interleukin 2 IL 2 were heterogeneous with respect to cell surface markers of progenitor as well as effector cells. Negative selection of cells with antibodies and complement or positive selection by fluorescence-activated cell sorting unequivocally showed that LAK effector cells consisted of at least two clearly distinct populations, the relative contribution of which was dependent on donor organ and target cells studied. Approximately 40% of the cytotoxic activity of spleen-derived effector cells active against the NK-resistant targets EL-4 or MCA-5 was eliminated by treatment with antibodies to the NK-markers asialo-GM1 and NK 1 (NK-LAK). Approximately 60% of cytotoxic activity was associated with cells expressing the T cell marker Lyt-2, lacked NK 1, and was lacking or expressed only small amounts asialo-GM1 (T-LAK). The NK-LAK cells were of greater importance for the cytotoxic activity against the standard NK target YAC-1, although T-LAK cells also excerted significant cytotoxicity against this cell line. Limiting dilution analysis estimated that the minimal frequency of precursors developing into cells with cytotoxic activity against EL-4 was 1/6700 in spleen and 1/4200 in peripheral blood. The frequency of cells developing into cytotoxic effectors against YAC-1 cells was 1/3700 and 1/1450 in spleen and peripheral blood, respectively. Depletion of progenitor cells from spleen or peripheral blood expressing NK 1 or Lyt-2 by treating the cells with antibodies to these structures and complement indicated that NK-1-expressing cells were the dominating progenitor of the LAK cells irrespective of target cells used. Culture of murine lymphoid cells from spleen or peripheral blood with high concentrations of IL 2 results in the emergence of two different killer cell populations with phenotypic similarities to NK and T cells, respectively, both being able to kill targets resistant to resting NK cells. In contrast to numerous earlier reports, we concluded that LAK cells are heterogeneous with respect to surface markers, with a major population of LAK cells apparently representing IL 2-activated cells expressing cell surface markers associated with NK cells.

Animals↗
PubMed1987

Selective induction of OX19+ (CD5+) or OX19- (CD5-) alloreactive cytolytic lymphocytes in the rat.

The phenotypes of alloselective cytolytic lymphocytes of the rat are defined by staining of peritoneal cells of alloimmunized donors with monoclonal antibodies, sorting in a cytofluorometer and evaluating cytolytic capacity in a 51Cr-release assay. We demonstrate that alloimmunization of BN rats can result in either OX19+ (CD5+) or OX19- (CD5-) cytolytic alloselective lymphocytes and show that the OX19- (CD5-) cytolytic cells are OX34+ W3/25- (CD4-) OX8+ (CD8+) lymphocytes not exposing surface Ig. It is further demonstrated that the appearance of CD5+ and CD5- cytolytic alloselective lymphocytes are mutually exclusive; immunization with (WF X BN) F1 cells leading exclusively to appearance of OX19+ effector cells while immunization with WF cells leads to OX19- effector cells. Alloimmunization of WF rats only results in appearance of OX19+ cytolytic lymphocytes.

Animals↗
PubMed1987

Abrogation of staphylococcal enterotoxin A-induced suppressor cell activity by the anti-Tac monoclonal antibody.

Human mononuclear cells stimulated with staphylococcal enterotoxin A (SEA) for 2-6 days significantly suppress [3H]thymidine incorporation and reduce the levels of interleukin 2 (IL-2) and interferon (IFN) in culture medium when added to fresh, polyclonally activated mononuclear cells. The inhibitory capacity of the cells correlates well with the expression of IL-2 receptors. Lymphocytes obtained 3 days after stimulation with SEA, when the IL-2 receptor expression is high, are more potent inhibitors than cells obtained 2, 6, 11 or 14 days after stimulation, when the IL-2 receptors are less expressed on lymphocytes. T4+ and T8+ cells were both found to be inhibitory. Irradiation of the cells with 15 Gy before stimulation with SEA reduced but did not eliminate their suppressive capacity. The expression of the IL-2 receptor was lower in the irradiated cells. Irradiation or mitomycin-C treatment of cells after 3 and 5 days of SEA exposure had no effect on their inhibitory capacities. Pretreatment of the cells with IL-2 could partially reverse their suppressive effect on recorded IL-2 levels of stimulated fresh cultures. A complete reversal was obtained with the anti-Tac monoclonal antibody, which binds to the IL-2 receptor. The collective data show that the SEA-induced suppression of IL-2 activity in lymphocyte culture medium is not due to a suppression of the IL-2 production but rather depends on depletion of IL-2 due to absorption of IL-2 from the culture medium.

Antibodies, Monoclonal↗
PubMed1987

Catalase and lipopolysaccharide enhance proliferation in the rat mixed lymphocyte reaction.

Proliferation of rat spleen cells in a mixed lymphocyte culture was amplified fivefold or more in the presence of 2000 units of catalase/ml, as measured by [3H]thymidine incorporation. A similar effect was observed with 1 microgram of lipopolysaccharide (LPS)/ml. Addition of polymyxin B abrogated the promotional effect of LPS, but not that of catalase. These results indicate that the hydrogen peroxide generated by some cells in the rat spleen cell mixed lymphocyte culture suppresses the proliferative response. The demonstration that removal of plastic adherent cells (reducing the percentage of monocytes/macrophages by 75-80%) also results in a 5- to 10-fold increase in a subsequent MLR, indicates that some of the adherent cells may be the producers of hydrogen peroxide, which at higher concentrations suppresses the T-cell proliferation. The enhanced proliferation was not mainly due to increased interleukin 2 (IL-2) production, since the IL-2 concentrations of catalase and LPS-containing cultures were lower than those of control cultures.

Animals↗
PubMed1986

Magnetic carbohydrate nanoparticles for affinity cell separation.

Magnetically responsive nanoparticles were prepared from enzymatically hydrolysed starch and magnetite. Two different monoclonal antibodies were covalently coupled to the particles. The antibody-coupled particles were in the size range of 100-300 nm and had an iron content of about 60%. Using 100 micrograms of magnetic particles (coupled with monoclonal mouse anti-rat Ig kappa light chain antibody) a very high depletion of surface Ig positive cells (mostly B-cells) from one million rat peripheral blood mononuclear cells could be achieved. The separation efficiency was evaluated by flow cytofluorometric analysis. This technique permits the detection of a small number of surface Ig positive cells among 10,000 negative cells.

Cell Separation↗
PubMed1986

The membrane phenotype of in vivo induced tumor selective cytolytic lymphocytes of the rat: a distinction from NK cells.

The phenotype of tumor selective cytolytic lymphocytes of the rat is defined by staining of peritoneal cells of tumor-immunized donors with the monoclonal antibodies OX19, OX8, and W3/25, sorting in a cytofluorometer and evaluating cytolytic capacity in a 51Cr release assay. It is shown that the tumor selective cytolytic lymphocytes bear the OX19 and OX8 markers but are lacking the W3/25 marker. It is also shown that the OX19+ lymphocytes do not contain any NK-like activity. The OX19 marker can therefore distinguish cells that execute selective cytolysis from cells with NK-like activities.

Animals↗
PubMed1986

Synergistic action of gamma interferon and catalase to reverse the suppressive effect of peritoneal macrophages on concanavalin A-induced lymphocyte proliferation.

The suppressive effect of normal rat peritoneal exudate cells (PEC) on concanavalin A (Con-A)-induced lymphocyte proliferation was studied. Partial suppression of proliferation was obtained by adding 3% PEC and complete suppression was observed with 6% PEC. The suppressive effect was mediated by W3/25+ plastic-adherent macrophages, which constitute about 60% of normal PEC. Addition of PEC prior to, simultaneously with, or 24 h after, but not 48 h after, the stimulation of lymphocytes with Con A resulted in suppression. Suppressed cultures produced normal or slightly increased amounts of interleukin 2 (IL-2), but the expression of the IL-2 receptor on lymphocytes was decreased. Pre-exposure of PEC to gamma interferon (IFN-gamma) resulted in decreased suppression, whereas IFN-gamma added simultaneously with the lymphocytes had no effect. Catalase reversed PEC-induced suppression and significant synergistic effects were recorded when combined with IFN-gamma. Even completely suppressed cultures were effectively protected from suppression. Indomethacin and combinations of indomethacin with catalase or IFN-gamma did not result in additional protection from PEC-mediated suppression.

Animals↗
PubMed1986

Evidence for the existence of W3/13+ monocytes in the rat.

Rat blood mononuclear cells were studied with W3/13, OX19, and W3/25 monoclonal antibodies in a dual staining procedure. Cells recognized as W3/13+ OX19- W3/25+ showed a high light scatter pattern were plastic adherent and exhibited spreading, and were identified as monocytes when stained with May-Grunwald-Giemsa. This evidence suggests that at least a subpopulation of monocytes/macrophages are W3/13+.

Animals↗
PubMed1986

Immunological abnormalities in a child with constitutional aplastic anemia.

This case report describes a child with severe constitutional hypoplastic anemia and Seckel's syndrome. Immunological analysis on mononuclear peripheral blood cells revealed an abnormally low ratio of T-helper to T-suppressor/cytotoxic cells and a highly increased number of HLA-DR-positive T suppressor/cytotoxic cells. Interferon-gamma and interleukin-2 production by mitogen-stimulated peripheral blood mononuclear cells was slightly reduced, and no spontaneous production of these lymphokines was seen. The immunological abnormalities demonstrated in this case of constitutional aplastic anemia may indicate common features with acquired aplastic anemia.

Abnormalities, Multiple↗
PubMed1984

Comparison of immune responses induced by rat RT-1 antigens presented as inserts into liposomes, as protein micelles and as intact cells.

Partially purified rat transplantation antigens (RT-1) were inserted into liposomes composed of various types of lipids and used for immunization. The immune responses induced by the liposomes were compared with responses induced by RT-1 as protein micelles, alone or emulsified in Freund's incomplete adjuvant, or intact cells. Liposomes gave generally a higher humoral response than protein micelles. Each type of RT-1 immunization gave a particular pattern of specific Ig (sub)class responses. Freund's incomplete adjuvant was not only lacking in potentiating effect on low protein dose immunization but had a significant inhibitory effect. Besides intact cells only distearoyl-phosphatidylcholine liposomes had the potential to induce a cell-mediated cytotoxic response.

Animals↗
PubMed1980

Induction of transplantation immunity to rat colon carcinoma isografts by implantation of intact fetal colon tissue.

The objective of this study was to demonstrate whether intact fetal colon tissue can induce immunity to large-bowel cancer isografts. Adult rats were immunized against fetal antigens by implantation of mitomycin-C-treated intact fetal colon tissue beneath the renal capsule. Control animals received implants of pieces of intact adult colon tissue. Kidneys containing the implants were removed after 3 or 5 weeks and the rats were challenged with isografts of a 1,2-dimethylhydrazin (DMH)-induced colon carcinoma. Significant inhibition of tumor growth was observed in immunized groups compared to controls. The present results indicate that some embro-fetal antigens expressed in intact colon tissue of 13 to 15-day-old fetuses are also expressed in colon carcinoma cells and can act as transplantation antigens.

Animals↗
PubMedDate not supplied

Targeting of superantigens.

The bacterial superantigen staphylococcal enterotoxin A (SEA) is an extremely potent activator of T lymphocytes when presented on MHC class II antigens. In order to induce T lymphocytes to reject a tumor, we substituted the specificity of SEA for MHC class II molecules with specificity for tumor cells by combining SEA with a MAb recognizing colon carcinomas. Chemical conjugates or recombinant fusion proteins of the MAb C215 and SEA retained excellent antigen binding properties whereas the binding to MHC class II was markedly reduced. The hybrid proteins directed SEA responsive T cells to tumors with specificity determined by the specificity of the MAb. Significant tumor cell killing was obtained at picomolar concentrations of the hybrid proteins and was the result of direct cell mediated by cytotoxicity as well as production of tumoricidal cytokines by T cells. Targeting of superantigens represents a novel approach to specific immunomodulation and deserves further study as a potential therapy for malignant disease.

Antibodies, Monoclonal↗
PubMedDate not supplied

Preparation and characterization of conjugates of monoclonal antibodies and staphylococcal enterotoxin A using a new hydrophilic cross-linker.

Conjugates between monoclonal antibodies recognizing human cancer cells and the superantigen staphylococcal enterotoxin A (mAb-SEA) represent a potential novel approach to tumor therapy. Such mAb-SEA conjugates direct T-cells to lyse colon carcinoma cells in vitro. The synthesis of mAb-SEA conjugates which were prepared by introducing thiol groups on SEA and iodoacetyl or maleimide groups on mAb forming a stable thioether linkage between SEA and mAb is described. A hydrophilic spacer, composed of repeated ethylene oxide units, was constructed to increase the distance between SEA and mAb, preserving biological activity of both proteins. The degree of modification of mAb with SEA was determined with SDS-PAGE. Variables influencing the composition of the conjugates and their effect on the tumor-cell cytotoxicity were studied and optimal conditions for the synthesis were established. Functionally active mAb-SEA conjugates were prepared from a panel of different mAb and T-cell-dependent cytotoxicity against several human cancer types including colon, ovarial, breast, and renal cancer was obtained. This suggests that mAb-SEA conjugates may be of value in the treatment of human neoplastic disease.

Antibodies, Monoclonal↗
PubMedDate not supplied

Linomide and antibody-targeted superantigen therapy abolishes formation of liver metastases in mice.

Hematogenous spread of tumor cells and metastasis formation in the liver are insidious aspects of cancer progression and are not frequently amenable to curative treatment. We examined the effect of Linomide and antibody-targeted therapy against the formation of hepatic metastases in vivo. For this purpose, syngenic B16 melanoma cells transfected with GA733-2 (a human colon cancer cell surface antigen) were injected into a mesenteric vein of C57/Bl6 mice. To test bacterial superantigen (Sag) targeting for immunotherapy of liver metastases, we used genetically fused proteins consisting of SEA and a Fab moiety of a GA733-2 tumor-reactive antibody (C215Fab-SEA). Linomide dose-dependently reduced hepatic metastases, and at 300 mg/kg this reduction was more than 80%. Treatment with C215Fab-SEA decreased metastases formation by 49% and the combination of Linomide and C215Fab-SEA was found to completely abolish liver metastases (>99% reduction). Taken together, our novel data suggest that Linomide and antibody-targeted superantigen therapy individually markedly reduce and together abolish liver metastases. Considering that current therapy of hepatic metastases is mainly limited to surgical resection in a subgroup of patients, these findings indicate that Linomide alone or in combination with antibody-targeted superantigen may provide a novel approach against liver metastases.

Adjuvants, Immunologic↗