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Biomedical subjects

P Ralph

Publications and source records attributed to P Ralph.

At least 73 records · Page 4Linked to original sources
PubMed1983

Suppression of natural killer activity in human blood and bone marrow cultures by bone marrow-adherent OKM1-positive cells.

Maintenance and regulation of natural killer (NK) cell activity in human bone marrow cultures were studied using K562 leukemia cells as targets. Culture of bone marrow cells in medium supporting long-term generation of myeloid cells resulted in a rapid loss of NK activity in 1-3 days. In contrast, antibody-dependent cytotoxicity to an NK-resistant tumor was maintained for more than 7 weeks. Horse serum, a component of the myelopoietic culture medium, was found to diminish NK cytotoxicity of blood and bone marrow cultures whereas hydrocortisone supplement did not. In addition, an adherent cell is present in bone marrow which greatly inhibits NK activity. Nonadherent bone marrow cells exhibited higher cytotoxicity than unfractionated cells at all days of culture; adherent cells were not cytotoxic to K562. Purified adherent marrow cells inhibited the cytotoxic capacity of nonadherent blood or marrow mononuclear cells during coculture. Indomethacin, an inhibitor of protaglandin synthesis, augmented levels of NK activity in cultures of bone marrow cells, indicating that macrophages may be suppressing this effector function via prostaglandins. Further identification of the adherent suppressor cells came from experiments in which suppression was prevented by treatment of the adherent cells with monoclonal OKM1 antibody plus complement. This study shows that bone marrow-adherent OKM1-positive cells, presumably macrophages, negatively regulate NK activity, and it defines conditions for analysis of the generation and/or positive regulation of NK cells in human bone marrow.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1983

Colony-stimulating factors and regulation of macrophage tumoricidal and microbicidal activities.

Conditioned medium from antigen- or mitogen-stimulated spleen cells, lymphokines, contained factors that induced formation of granulocyte and macrophage colonies in cultures of bone marrow cells (CSF). Lymphokines also contained factors that induced macrophage non-specific tumoricidal activity against fibrosarcoma 1023, antibody-dependent tumoricidal activity against lymphoma 18-8, and antimicrobial activities against amastigotes of the protozoan parasite, Leishmania tropica. The factors that regulated macrophage effector functions, however, were different from those that induced colony formation, and could be distinguished from CSF by Sephadex gel chromatography or heat sensitivity. To further analyze a role for CSF in induction of macrophage effector activities, conditioned medium from several nonlymphoid cell sources (L-929, WEHI-3, and endotoxin-treated lung cells) were assayed for CSF activities and capacity to induce tumoricidal and microbicidal activities. Conditioned medium that contained either macrophages CSF (CSF-1) or the factor that induced formation of both macrophage and granulocyte colonies failed to activate macrophages for effector activities against fibrosarcoma 1023, lymphoma 18-8, and L. tropica amastigotes (either resistance to infection or intracellular destruction). These data suggest that CSF has no direct role in activation of macrophages for tumoricidal and microbicidal activities against these targets.

Animals↗
PubMed1983

Endocytosis by the mononuclear phagocyte system and autoimmune disease.

The mononuclear phagocyte system, formerly called the reticuloendothelial system, is an important element in basic immunology, cell biology, and clinical disease. Secretory products participate in inflammation and immunoregulation. Endocytosis mediated by specific receptors for immunoglobulin and complement or by other opsonins is important in removal of damaged self or foreign particles. The ability to assess receptor-specific endocytosis has led to the recognition of Fc-receptor dysfunction in certain autoimmune diseases. This defect in membrane receptor function, whether inherited or acquired, may be important in the pathogenesis of these diseases.

Animals↗
PubMed1983

IgM and IgG secretion in human B-cell lines regulated by B-cell-inducing factors (BIF) and phorbol ester.

Human B-cell lines were screened for stimulation of immunoglobulin production by incubation with lymphokine (LK) or tumor promoter, phorbol myristic acetate (PMA). One group of lines had essentially no immunoglobulin-secreting cells (ISC) under any condition (less than 0.01%), detected by a reverse plaque assay. Another group of lines had high levels of ISC (greater than 5%) which was not increased substantially by inducing agents. In a third group of IgM and IgG lines, there were intermediate levels of ISC which could be increased by LK, PMA or both agents. No evidence for isotype switching in a number of stimulated IgM and IgG cell lines was detected. Clone SKW6.4 of an IgM line was highly responsive to a B-cell-inducing factor (BIF) in LK. BIF for SKW6.4 and IgG line ARH-77 was weakly binding to DEAE cellulose, about 20,000 mol. wt., and separable from IL-2 by blue agarose chromatography. IL-2 did not stimulate secretion in SKW6.4 with or without purified BIF. In Clone SKW6.4, BIF stimulated ISC per recovered cell up to 30-fold by day 1 of culture, and these plateau levels of about 6% ISC were maintained for longer than 4 days. Treatment of cells with BIF for less than 1 day was sufficient to produce maximum effect on this clone for the succeeding 4 days. Cells stimulated with BIF and then subcultured at day 3 without BIF showed ISC numbers increasing but at a slower rate than the total population, suggesting that the induced differentiation state is long-lived (half-life of % ISC greater than 6 days) and that ISC produce some daughter ISC.(ABSTRACT TRUNCATED AT 250 WORDS)

B-Lymphocytes↗
PubMed1983

Cell-mediated lysis of tumor targets directed by murine monoclonal antibodies of IgM and all IgG isotypes.

Seven murine monoclonal antibodies to antigens expressed on T lymphoma targets were tested for directing antibody-dependent cellular cytotoxicity (ADCC). Peptone-induced peritoneal exudate macrophages, the LPS-stimulated RAW264.10 cell line, and human blood nonadherent mononuclear leukocytes were used as effector cells. All six IgG monoclonals tested, representing the four murine IgG isotypes and directed against four antigens (Thy-1.2, H-2k, Ly-2.1, Ly-9.2), were all active in ADCC. In contrast, an IgM anti-Thy-1.2 showed no activity despite very high C-cytotoxic titers. Thus, there does not seem to be any restriction among IgG classes for directing ADCC to tumor targets mediated by murine macrophages or human K cells.

Animals↗
PubMed1983

Lymphokine inducing "terminal differentiation" of the human monoblast leukemia line U937: a role for gamma interferon.

The human monoblast leukemia line, U937, is growth-inhibited and induced to develop markers of mature monocytes by lymphokine preparations. Lymphokine is cytostatic and induces expression of Fc receptors in U937 and in myelomonocytic leukemic lines RC-2A and KG-1, but does not have these effects on T- and B-lymphocytic lines. In addition to previously described properties, including complement receptors, phagocytosis, and antibody-dependent cellular cytotoxicity (ADCC), Mac-1 and Mac-3 surface antigens defined by monoclonal antibodies are induced on U937 cells by lymphokine and phorbol ester. The Mac-1 surface component appears to have a regulatory role in differentiation of the monocyte lineage line, since antibodies to this antigen block the induction of Mac-3 antigen. The lymphokine activity was concentrated by salt precipitation and characterized by ion-exchange and size chromatography. Fractions of about 40,000 daltons were responsible for growth inhibition and induction of Fc receptors and Mac-1 antigen in U937 cells. However, ADCC was not induced in U937 by individual fractions of lymphokine, suggesting that this cytotoxic capacity may be regulated by a lymphokine of a different size, which is only effective after initial maturation steps. Since gamma-interferon is present on the 40K size range of lymphokine, the possibility that interferon is a differentiation modulator for the monoblast cells was investigated. Highly purified gamma-interferon (10(7) U/mg protein) at 10-300 U/ml inhibited growth and induced Fc receptors in U937 similar to the effect of lymphokine. The Fc-receptor-inducing activity of lymphokine was inhibited by a neutralizing monoclonal antibody to gamma-interferon, suggesting that this differentiation factor in lymphokine is gamma-interferon.

Animals↗
PubMed1983

Lactoferrin, transferrin and acidic isoferritins: regulatory molecules with potential therapeutic value in leukemia.

In the process of evaluating roles for purified preparations of lactoferrin, transferrin and acidic isoferritins in the regulation of myelopoiesis, it was found that: (1) values reported for lactoferrin in the serum and plasma of normal donors are in most cases an over-estimation, (2) lactoferrin suppresses the production/release of granulocyte-macrophage colony stimulatory factors (GM-CSF) from monocytes in the absence of T-lymphocytes and also suppresses the production/release of acidic isoferritin-inhibitory activity from monocytes, (3) lactoferrin, transferrin and acidic isoferritins act on their specific target cells which express Ia-like antigens, (4) lactoferrin and transferrin act in vivo to suppress rebound myelopoiesis in mice recovering from sublethal dosages of Cytoxan, with preliminary observations suggesting that lactoferrin has a greater apparent effect on the bone marrow and transferrin has a greater apparent effect on the spleen, (5) active lactoferrin derives from Fc receptor positive subpopulations of PMN from patients with CML as well as from normal donors, but the percentage of Fc receptor containing PMN is lower in CML, as is the amount of active lactoferrin found in their PMN, and (6) lactoferrin, transferrin and acidic isoferritins suppress the colony formation of U937 clonogenic cells, with lactoferrin and transferrin decreasing the release of growth factors from U937 cells which are needed to stimulate U937 colony formation, and lactoferrin and acidic isoferritins suppress the colony formation of WEHI-3 cells, with lactoferrin decreasing the release of growth factors from WEHI-3 cells which are needed to stimulate WEHI-3 colony formation. Speculation on the potential usefulness of these iron binding glycoproteins to control of disease progression is given in the discussion.

Animals↗
PubMed1982

IgM- and IgD-bearing peripheral blood lymphocytes differentiate to IgM but not IgG or IgA immunoglobulin-secreting cells.

Human peripheral blood mononuclear cells were depleted of surface IgM+ or IgD+ cells and assayed for mitogen-induced differentiation to immunoglobulin-secreting cells (ISC) of IgM, IgG and IgA classes. Stimulatory agents included T cell-dependent pokeweed mitogen, B cell mitogen Staphylococcus aureus bacteria strain Cowan I, and a combination of the two which gives uniform, high levels of ISC from all normal donors. Depletion of either IgM- or IgD-bearing B lymphocytes resulted in loss of cells bearing the other Ig class and blocked most of the mitogenic reactivity to anti-IgM and anti-IgD. Proliferative responses to Cowan I in these depleted populations were about 20% that of unfractionated mononuclear cells. Depletion of T cells increased the mitogenic response to Cowan I and to the two antibody preparations, showing that they are T-independent mitogens. Depletion of IgD+ cells caused partial loss of mitogen-induced IgM ISC (22%-60% of unseparated controls) but no loss of IgG or IgA ISC. Depletion of IgM-bearing cells caused complete loss of IgM ISC, but no loss of IgG or IgA ISC. We previously demonstrated that anti-IgM ISC, but no loss of IgG or IgA ISC. We previously demonstrated that anti-IgM antibody blocked mitogen induction of Ig secretion of these three classes in spleen cells, but only IgM secretion in blood mononuclear cells. Together, the results suggest that the majority of cells in normal blood responding to mitogens to mature to IgG or IgA production belong to IgM-, IgD- B cell subjects, in contrast to precursors of secreting cells for these isotypes in the spleen. Thus, these blood precursors appear to be more mature than the corresponding spleen cells.

Antibodies, Anti-Idiotypic↗
PubMed1982

Three distinct stages of B-cell defects in common varied immunodeficiency.

B-lymphocyte function of 15 patients with primary common varied immunodeficiency or related disease were examined. All patients had low serum levels of IgM, IgG, and IgA, but 12 of 15 patients had nearly normal numbers of peripheral blood B lymphocytes. Mononuclear cells and B cells from peripheral blood were assayed for B-cell mitogenic responses to anti-Ig mu chain antibodies or to Staphylococcus aureus strain Cowan I (referred to as Cowan I), and for differentiation to Ig-secreting cells of IgM, IgG, and IgA classes in the presence of Cowan I and pokeweed mitogen or T-cell factor. The patients all showed profound B-cell defects in one or more of the assays and could be divided into three approximately equal groups based on their responses. The first group showed normal proliferation in response to the two B-cell mitogens and near normal numbers of IgM-secreting cells but no IgG- or IgA-secreting cells. B cells in the second group showed proliferative responses to Cowan I or anti-mu, but no differentiation to Ig-secreting cells. The third group had no B-cell proliferative responses or differentiation in our assays. In several patients from each group, (i) helper T cells were functional in Ig-secreting-cell responses with purified normal B cells, (ii) patient T cells did not significantly suppress formation of Ig-secreting cells by normal cells in coculture, and (iii) removal of T cells with addition of T-cell-replacing factor, or partial removal of monocytes, did not alleviate any of the defects. These studies show that primary B-cell defects in common varied immunodeficiency occur at several levels, probably representing blocks at different stages of differentiation.

Adolescent↗
PubMed1982

Human lymphoma-lymphoma hybrids and lymphoma-leukemia hybrids. I. Isolation, characterization, cell surface markers, and B-cell markers.

Four new somatic cell hybrids were obtained by fusion of various Burkitt's lymphoma (BL)-derived cell lines that had different selective markers: Raji-P3HR-1, Daudi-Raji, and a P3HR-1-P3HR-1 "autohybrid" derived from two P3HR-1 sublines. In addition, a hybrid was obtained between the Daudi (BL) line and the human leukemia cell line K562. The hybrids were extensively characterized by means of chromosome, isozyme, and HLA surface markers. The phenotypic differences between the parent cell lines allowed some conclusions with respect to the expression of latent Epstein-Barr virus (EBV) genomes, C3 and EBV receptors, and of immunoglobulin and beta 2-microglobulin-HLA expression as well as the influence of the leukemia cell (K562) genome on B-cell properties in the Daudi-K562 hybrid. B-cell and differentiated markers of these hybrids were characterized. High-level expression dominated for the marker C3 and EBV receptors, which showed a good correlation coefficient of 0.84, as was true for Fc receptors and surface immunoglobulin. The Daudi-K562 hybrid showed loss of all B-cell markers but retention of the leukemia cell markers (e.g., hemoglobin synthesis).

Animals↗