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Biomedical subjects

P Ralph

Publications and source records attributed to P Ralph.

At least 127 records · Page 7Linked to original sources
PubMed1977

Regulation of clonal B-lymphocyte proliferation by anti-immunoglobulin or anti-Ia antibodies.

Regulatory effects of antibodies to cell-surface antigens have been examined in an in vitro clonal assay for B lymphocytes. In this system, cell contact is prevented by a semisolid gel matrix, and many of the factors affecting cell proliferation have been described. Inclusion of antibodies to mu, kappa, or Ia in these cultures reduced the size and number of proliferating foci. As little as 1 microgram/ml of anti-mu antibody prevented formation of colony-size aggregates. Pretreatment with these antibodies before culture followed by wash had no effect. Divalent F(ab')2 anti-IgM antibodies were as effective as intact antibodies, but monovalent Fab fragments were not inhibitory. Anti-gamma1 antibodies, anti-alpha antibodies, or cell-bound antigen-antibody complexes had no effect on clonal proliferation. These findings suggest that a negative signal can be delivered to B cells during a critical period of their activation via certain surface receptors. Modifications in culture conditions result in the selective propagation of different B-cell subpopulations.

Animals↗
PubMed1977

Cell-free granulocyte colony inhibiting activity derived from human polymorphonuclear neutrophils.

Human PMN (non-adherent: density greater than 1.070 g/cm3) were used to prepare cell-free colony inhibiting activity (CIA). Intact PMN, PMN conditioned media (serum-free or serum-containing) and supernatant from immediately lysed PMN equally reduced the numbers of spontaneous bone marrow (density less than 1.070 g/cm3; depleted of PMN) colonies and clusters. Addition of CIA reproducibly reduced colony and/or cluster numbers by 35-70%. CIA was heat labile being inactivated at 37 degrees C. Daily additions of CIA reduced colony numbers even further; inhibition was dependent on [PMN] used to prepare CIA and on the potency of stimulation produced by colony stimulating cells (CSC). PMN from some patients with leukemia were inactive as inhibitors and did not condition media with CIA. All experiments were thereafter controlled by parallel assessment of supernatant of lysed PMN not demonstrating any CIA. CIA appears to be not only stored in PMN but released from viable, as well as degranulating PMN. Although not species-specific, CIA was specific in its nontoxic action on CSC; colony forming cells and cell-free colony stimulating activity were not affected. The influence of CIA on CSC could be reversed within 10 minutes, but not within 35 minutes of incubation. CIA may have possible physiological relevance.

Animals↗
PubMed1977

In vitro regulation of a mouse myelomonocytic leukemia line adapted to culture.

Regulation of the growth and production of granulocyte colony-stimulating activity (CSA) by WEHI-3 cells, a lysozyme-secreting mouse cell line adapted to culture, was investigated in vitro. WEHI-3 cloning efficiency is not enhanced by exogenously added CSA. However, WEHI-3 cloning efficiency in agar was suppressed by an activity in human polymorphonuclear neutrophil extract (colony-inhibiting activity) which inhibits endogenous WEHI-3 CSA production. The addition of increasing concentrations of WEHI-3- or L cell-conditioned medium containing CSA to CIA-depressed WEHI-3 agar cultures resulted in graded increases of cloning efficiency to that of the untreated sample. Testosterone, Deca-Durabolin, and bacterial lipopolysaccharide increased production of CSA by WEHI-3 cells and overcame colony-inhibiting activity-mediated suppression of CSA production, even when activating agents were added 1 day after the addition of colony-inhibiting activity. The activating agents had no direct stimulatory effect on normal mouse marrow colony-forming cells and did not enhance CSA activity. WEHI-3 cells respond to growth inhibitory and stimulatory activities and can serve as an in vitro model for studying the regulation of neoplastic cells.

Animals↗
PubMed1977

Stimulation of a human B-lymphocyte line by anti-immunoglobulin and its concanavalin A-induced suppression by a T-cell line.

The effect of anti-immunoglobulin (anti-Ig) on cultures of established human B-cell lines was studied to develop models for the initiation and regulation of immune responses. DNA synthesis in one line, BM, measured by [125I]iododeoxyuridine (IUdR) incorporation, was stimulated by anti-Ig when the continuously proliferating cultures approached high cell density. One of four lines, BJAB, was very sensitive to inhibition of DNA synthesis by anti-Ig at all cell concentrations. Of four human T-cell lines tested for suppressor activity, the CEM line was found to be activated by concanavalin A (Con A) to inhibit the anti-Ig stimulation of BM cells. No cytotoxic activity was detected in Con A-treated CEM cells. Both the anti-Ig stimulation of BM and Con A-induced suppression by CEM occurred with cloned cell lines in long-term culture, in the absence of helper or accessory cells.

Antibodies, Anti-Idiotypic↗
PubMed1977

Direct toxic effects of immunopotentiators on monocytic, myelomonocytic, and histiocytic or macrophage tumor cells in culture.

Four murine monocyte, myelomonocyte, and histiocyte or macrophage tumor cell lines adapted to culture were growth inhibited by one or more of the following macrophage-activating substances: Mycobacterium bovis, Bacillus Calmette-Guérin strain, zymosan, lipopolysaccharide, and dextran sulfate, as well as tuberculin purified protein derivative, but not latex beads. Lipopolysaccharide was effective with one line at 4 ng/ml. All four lines actively phagocytosed zymosan and latex beads. In many cases the growth inhibition was apparently immediate but only cytostatic, and cell proliferation resumed upon removal of the drug. Bacillus Calmette-Guérin, live or boiled, was toxic to some of the tumor lines. Synthesis of lysozyme by all the cell lines in the monocyte series and production of granulocyte colony-stimulating factor by the myelomonocytic leukemia were not inhibited during several days of zero growth conditions in the presence of drugs. Since these agents had no direct effect on other hematopoietic tumor types (myeloma, T-lymphoma, mastocytoma) at the same or up to 10(4) higher concentrations, it is proposed that the sensitive tumors retain specific receptors for immunostimulants, either at the cell surface or within the cell in the case of phagocytosable particles. The binding of these agents to physiological receptors leads to stimulation and mitogenesis in normal macrophages and lymphocytes but leads to growth inhibition without affecting differenetiated functions in the corresponding tumor lines.

Adjuvants, Immunologic↗
PubMed1977

Antibody-dependent killing of erythrocyte and tumor targets by macrophage-related cell lines: enhancement by PPD and LPS.

Five murine macrophage or monocyte-related tumor cell lines in culture were compared for antibody-dependent lysis (ADL) of a tumor target (T lymphoma EL4) and lysis and phagocytosis of sheep erythrocytes (RBC). Some lines were effective only with RBC targets, while others were capable of lysing these and tumor targets. Both murine alloantisera to H-2 and Thy 1.2 antigens on the target cells and rabbit anti-mouse spleen and anti-mouse thymus sera directed target lysis, while normal mouse or rabbit sera were inactive. Preincubation of macrophage line RAW264 with lipopolysaccharide (LPS) or purified protein derivative from Mycobacteria (PPD) for 2 days resulted in an average of 76% or 86% increase, respectively, in ADL of RBC, although there was no stimulation in RBC phagocytosis or in nonspecific or antibody-dependent lysis of tumor targets. These results indicate that macrophage cell types are capable of antibody-dependent tumor lysis, that macrophages are probably heterogeneous in effector cell activities, and that they can be stimulated to increased ADL in the complete absence of other cell types.

Animals↗
PubMed1976

Properties of the K562 cell line, derived from a patient with chronic myeloid leukemia.

The K562 cell line derived from a CML patient in blast crisis was examined for properties of B and T lymphocytes and cell lines. K562 lacks the B markers of immunoglobulins, Epstein-Barr virus (EBV) genome and associated nuclear antigen, and receptors for EBV. A low proportion of cells from rosettes with sheep erythrocytes, the frequency of which is considerably increased after neuraminidase treatment. Unlike B lines but like T lines, K562 cells are lysed rapidly by C'/Fc receptor-positive human blood leukocytes and do not stimulate MLC reactions. On the other hand, K562 lacks T antigen, high radiosensitivity and sensitivity to growth inhibition by thymidine. The cells do not contain N-APase, an enzyme found in all lines derived from lymphoid cells and in lymphoproliferative diseases. By scanning electron microscopy, K562 cells were seen to be rounded and relatively smooth, with small numbers of short microvilli resembling undifferentiated leukemic cells. A few cells had narrow ridge-like profiles and small ruffles similar to granulocytic leukemic cells. K562 is strongly positive for immunoglobuln Fc receptors and pinocytosis, but does not phagocytose or mediate antibody-dependent phagocytosis or cytolysis. Among histochemical stains, K562 is positive for esterase, lipid, and acid phosphatase. There seems to be no doubt that K562 is not a B cell line. While it has some T cell properties, these are not exclusive. Some of its characteristics indicate that it is probably not lymphoid. Due to its low level of differentiation, its nature cannot be stated with certainty. On the basis of the possible presence of the cellular marker of chronic myeloid leukemia, the Ph chromosome, it may be regarded as belonging to the granulocytic series of cells.

Alkaline Phosphatase↗
PubMed1976

Lysozyme synthesis by established human and murine histiocytic lymphoma cell lines.

A human cell line established in culture from a histiocytic lymphoma patient synthesizes and secretes the monocyte-granulocyte specific enzyme lysozyme. 18 other human cell lines with characteristics of T-lymphocyte, B-lymphocyte, Burkitt's lymphoma, non-Burkitt's lymphoma, myeloma, and bone marrow epithelial cells were not associated with lysozyme. Among murine cell lines, lysozyme was produced by (a) three histiocytic lymphoma or macrophage lines, which mediate antibody-dependent phagocytosis and cytolysis; (b) myelomonocytic leukemia line which also secretes myeloid colony-stimulating factor; and (c) a spontaneous lymphoma and an Abelson leukemia virus-induced lymphoma. Lysozyme-negative lines include another Abelson lymphoma, myelomas, T lymphomas, and mastocytoma.

Cell Line↗
PubMed1976

Growth of B-lymphocytes clones in semisolid culture is mitogen dependent.

A substance which was mitogenic for murine B lymphocytes in the presence of 2-mercaptoethanol was isolated from agar. Stimulating activity of this material was stable to proteolysis or protein denaturants but was destroyed by periodate treatment. Agar-derived mitogen stimulation was distinct from that obtained with dextran sulfate or lipopolysaccharide and may define different populations of B lymphocytes.

Agar↗
PubMed1975

Differences in the surface proteins of mouse B and T cells.

We have selectively labeled the surface of mouse thymus-dependent (T) and thymus-independent (B) lymphocytes by means of lactoperoxidase-catalyzed iodination. Examination of the labeled proteins by electrophoresis in the presence of sodium dodecylsulfate followed by autoradiography revealed differences in the cell surface proteins of B and T cells. Proteins from labeled thymocytes, T cell lymphomas, and both normal and activated peripheral T cells give a broad band of radioactivity corresponding to at least two protein components with apparent molecular weights of 170,000 to 190,000. This band is absent from autoradiographs of iodinated B cell proteins, which instead have another band corresponding to a protein with an apparent molecular weight of about 220,000. We have shown that these T and B cell marker proteins are synthesized by the cell and are not serum components selectively bound to the cell surface. We have also established that these proteins are the major iodinated species precipitated from Nonidet P-40 cell lysates by rabbit anti-mouse lymphocyte serum, suggesting that they are the major antigens recognized by rabbit antibodies to mouse lymphocytes.

Animals↗
PubMed1975

Oncogenic transformation of murine lymphoid cells by in vitro infection with Abelson leukemia virus.

Spleen cell cultures stimulated to DNA synthesis by antigen or mitogen were infected with Abelson virus, a C-type RNA virus inducing nonthymic lymphomas in mice. After 3 days the cells were transferred to mice and caused 100 percent incidence of lymphomas in as few as 29 days. That a number of the tumors were of donor origin, as shown by female karyotypes in recipient male mice, indicated that cells infected by virus in vitro were transformed. The process depended upon both virus and stimulation of lymphocytes in culture. Lymphoid tumors did not develop in mice receiving cells from virus-infected cultures not exposed to antigen or mitogen.

Animals↗
PubMed1975

Reticulum cell sarcoma: an effector cell in antibody-dependent cell-mediated immunity.

A transplantable, murine reticulum cell sarcoma is described which exhibits the cytologic, adherence, and phagocytic properties of macrophages. It forms specific rosettes with erythrocytes in the presence of the corresponding anti-serum. The ascites cells mediate antibody-dependent cellular immunity as assayed by release of radioactivity from 51Cr-labeled erythrocytes. The contribution of contaminating host cells in the cytotoxic reaction was ruled out by growing the tumor in F1 mice and removing the host cells by anti-H2 serum and complement. The tumor cells have receptors for IgG2a and IgG2b immunoglobulins. The availability of a pure population of effector cells in the immune system allows study of the biochemical processes pursuant to lysis of foreign cells.

Animals↗