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Biomedical subjects

H M Grey

Publications and source records attributed to H M Grey.

At least 127 records · Page 7Linked to original sources
PubMed1980

Nature of hapten-modified determinants involved in induction of T cell tolerance and suppressor T cells to NDFB contact sensitivity.

Unresponsiveness to DNFB contact sensitivity induced by DNP-modified lymphoid cells (DNP-LC) is mediated by two separable pathways: a rapidly induced, long lasting inhibition of reactive T cell clones (donor tolerance), and a transient period of suppressor T cell (Ts) activity. The present report has examined the nature of the hapten-modified determinants responsible for the induction of these pathways by utilizing soluble DNP-LC cell lysate preparations as tolerogens. The results indicate that both DNP-modified MHC and non-MHC encoded determinants can mediate donor tolerance 7 days after tolerization. On the other hand, the induction of Ts requires DNP-modified MHC determinants, since DNP-LC lysates passed over lentil lectin or specific anti-H-2 immunoabsorbent columns lost their ability to induce Ts. Additional experiments showed that the injection of DNP-LC lysate compatible with the recipient strain at the H-2K and H-2D region of the MHC was sufficient for the induction of Ts. We propose that Ts induction involves the direct presentation of DNP-H-2 determinants to Ts precursors, whereas the induction of donor tolerance may involve host processing and presentation of DNP-modified membrane determinants in conjunction with host MHC structures.

Animals↗
PubMed1980

Antigen recognition by T cells. II. Intravenous administration of native or denatured ovalbumin results in tolerance to both forms of the antigen.

In the accompanying report, suppressor T cells were demonstrated that did not recognize cross-reactivity between native and denatured ovalbumin (N-OVA and D-OVA). Here we show that the T cell tolerance induced by i.v. injections of antigen does detect cross-reactivity between N-OVA and D-OVA. Mice that had been immunized with either N-OVA or D-OVA in adjuvant could be rendered profoundly unresponsive if either N-OVA or D-OVA, but not an unrelated protein, were injected i.v. Cross-tolerance was observed in assays of antigen-induced T cell proliferation and helper T cell activity. Tolerance was distinguished from suppressor T cell activity by three criteria: 1) specificity for N-OVA and D-OVA, 2) sensitivity to abrogation by cyclophosphamide, 3) duration of effectiveness. These results confirm observations made by others that suggest that tolerance is mediated by an additional mechanism(s) other than suppressor T cells. Based on a hypothesis that cross-reactivity between native and denatured antigen is related to macrophage processing of antigen, these data also suggest a critical role for processed antigen in the induction of tolerance when antigen is administered i.v.

Animals↗
PubMed1979

Studies on the cytophilic properties of human beta2-microglobulin. II. The role of histocompatibility antigens.

The mechanism by which exogenously added beta2m binds to lymphoid cells has been explored. In the mouse it has been shown that beta2m remains associated with plasma membrane macromolecules following solubilization with NP-40 and that approximately 25-30% of the binding could be accounted for by binding to H-2 antigens. No binding to mouse immunoglobulin or Ia antigens could be detected. The sites for binding of the remainder of the cell-bound beta2m were not determined. Whereas normal human lymphocytes showed little or no capacity to bind exogenously added beta2m, it was found that phytohaemagglutinin (PHA)-stimulated cells could bind beta2m. This binding occurred optimally 2 days after PHA stimulation. Approximately half of the binding could be accounted for by binding to HLA antigens. The possible significance of these findings with respect to cellular interactions involving major histocompatibility complex gene products in the immune response is discussed.

Beta-Globulins↗
PubMed1979

Heterogeneity of binding of human IgA subclasses to protein A.

The ability of human IgA myeloma immunoglobulins to interact with protein A-containing Staphylococcus aureus was examined. Some IgA1 and IgA2 immunoglobulins bound to S. aureus although others of both subclasses failed to do so. These results were obtained by using both direct binding of radiolabeled immunoglobulins to S. aureus and with inhibition-type assays. Binding was dependent on the Fc fragment of IgA since there was no binding to S. aureus by an F(ab')2 fragment of IgA1. Nonprotein A-containing bacteria did not bind these immunoglobulins and isolated protein A interacted with radiolabeled immunoglobulins. This strongly suggested that protein A was responsible for the observed binding to S. aureus. These data indicate, in contrast to previous reports, that there is no simple relationship between IgA subclass and the capacity to bind to protein A.

Binding Sites, Antibody↗
PubMed1978

Physicochemical separation of two distinct Fc receptors on murine macrophage-like cell lines.

By using radiolabeled myeloma proteins specific for each of two distinct Fc receptor activities on macrophage-like murine cell lines ("aggregated IgG FcR" activity and "monomer IgG2a FcR" activity), we have been able to detect solubilized FcR of both types in detergent lysates of these cells. The two solubilized Fc receptors can be distinguished and physically separated from one another by means of affinity chromatography and by sucrose gradient centrifugation. They also differ in their sensitivity to phospholipase C. The detergent solubilized monomer IgG2a FcR can be removed from solution with a Sepharose IgG2a column, has an S value of 4 to 5 and is resistant to phospholipase C. The solubilized aggregated IgG FcR does not bind to insolubilized IgG2a, has an S value of greater than 19, and is sensitive to phospholipase C treatment. We conclude from these studies that two different cell membrane macromolecules are responsible for the Fc receptor activities observed in macrophage-like cell lines.

Animals↗
PubMed1977

Receptors for IgG: subclass specificity of receptors on different mouse cell types and the definition of two distinct receptors on a macrophage cell line.

To evaluate subclass specificity and aggregate size requirements of IgG receptors on mouse cells, we measured binding of radiolabeled monomeric and BDB-aggregated mouse myeloma proteins fractionated into various sizes by means of gel filtration. Monomers, tetramers, and high molecular weight (approximately 10(7) daltons) aggregates were used. The various cells and cell lines studied could be segregated into three patterns of reactivity: (a) Macrophage and macrophage-like cell lines bound monomer IgG2a preferentially; high molecular weight IgG aggregates bound as follows: IgG1 = IgG2b = IgG2a. (b) Lymphoid lines D2N and S49 showed no capacity to bind monomer IgG2a; high molecular weight aggregates bound as follows: IgG1 = IgG2b less than IgG2a. (c) Other Thy-1-positive lymphoid cell lines (EL4 and L5178) and normal T and B cells showed no capacity to bind monomer IgG; high molecular weight IgG aggregates bound to a lesser extent than to cells of the first two categories in the following manner: IgG1 less than IgG2b greater than or equal to IgG2a. The variable pattern of reactivity of the macrophage-like cell lines with monomer and aggregated IgG suggested that two distinct receptors for IgG were present: one capable of binding IgG2a and another capable of binding all aggregates. Further evidence for this hypothesis was obtained by analysis of the inhibitory capacity of different IgG subclasses on the binding of aggregated IgG and monomer IgG2a to P388 cells. Inhibition of monomer IgG2a binding was effected only by monomer or aggregated IgG2a, whereas inhibition of binding of aggregated IgG1 or IgG2b was noted with aggregates of all three subclasses with some preferential inhibition by monomer IgG2b being observed. Furthermore, monomer IgG2b binding was preferentially inhibitable by monomer IgG2b. It is postulated from these data that two receptor sites are present on this macrophage-like cell line, one reactive with aggregates of all three subclasses as well as monomer IgG2b, and another receptor specific for monomer IgG2a which also binds aggregated IgG2a. Support of this concept was obtained by trypsinization experiments in which the binding of monomer IgG2a was markedly decreased by trypsin treatment of cells, whereas the binding of aggregated IgG2b was unaffected by this treatment.

B-Lymphocytes↗
PubMed1977

Mitogen activation of human chronic lymphatic leukemia cells. I. Synthesis and secretion of immunoglobulin.

The response of CLL (chronic lymphatic leukemia) lymphocytes to PHA, PWM, and Con A with respect to changes in surface markers and synthesis and secretion of immunoglobulin were examined. After PHA stimulation the percentage of cells bearing readily detectable surface immunoglobulin (SmIg) diminished rapidly whereas cells forming rosettes with sheep erythrocytes (E-rosettes) increased from less than 1% to 30 to 50%. The great majority of blast-transformed cells were E-rosette-positive cells with a small population of SmIg-positive blast cells also observed. Ig production in four of seven CLL lymphocyte populations was increased 2.5 to greater than 40-fold after 4 to 6 days of culture in the presence of PHA. In contrast, pokeweed mitogen did not affect Ig synthesis. Furthermore, the Ig secreted into the culture supernatant fluids from seven of eight CLL cases examined consisted almost entirely of free light chain molecules. In contrast, the cell lysates contained a significant proportion of intact Ig molecules. These results indicate that CLL cells can, under certain circumstances, be stimulated to synthesize and secrete increased amounts of Ig, but that there is a basic defect in the biosynthetic mechanism of these cells which result in the secretion of free light chains rather than intact immunoglobulin molecules.

B-Lymphocytes↗
PubMed1977

Solubilization and partial characterization of cell membrane Fc receptors.

We assayed detergent cell lysates and culture supernatant fluid of mouse cells for the presence of soluble FcR by means of a radioligand bioassay. Strict correlation was found between the amount of FcR present in soluble form and that found on intact cells. The soluble FcR of all cells tested, except mouse macrophages, behaved as lipoprotein by buoyant density centrifugation analysis and enzyme treatment. In the absence of detergent, soluble FcR sedimented as a 20S macromolecule; in detergent the material was 7 to 9S. It was readily bound by insolubilized IgG but not by insolubilized BSA or F(ab')2 fragments of IgG.

Animals↗
PubMed1976

PHA-induced activation of suppressor cells in normal human peripheral blood lymphocytes.

Normal human peripheral blood and tonsil lymphocytes can be stimulated to proliferate by phytohemagglutinin (PHA). When cells cultured with this mitogen for 3 days were transferred fo fresh autologous lymphocytes in fresh medium with PHA, the mitogen response of the fresh lymphocytes was suppressed. The suppression required the presence of viable cells, in that culture supernatants alone were not inhibitory and cell extracts showed only marginal inhibition. Approximately equivalent numbers of previously stimulated cells were required to produce optimal suppression of the PHA response of fresh cells. Cells irradiated after PHA stimulation were as effective as nonirradiated cells is causing suppression. PHA-stimulated cells also inhibited concanavalinA-induced proliferation and a mixed lymphocyte reaction. However, PHA-stimulated cells only partially inhibited the response to pokeweed mitogen. The suppressive effects were fully retained by a nylon-wool-enriched T-cell fraction but not by a B-cell-enriched fraction.

Cell-Free System↗
PubMed1976

Antigen heterogeneity of human B and T lymphocytes.

Rhesus monkeys were immunized with normal human lymphoid cells, cultured lymphoid cells, and chronic leukemic lymphocytes. Antisera were analyzed by cytotoxicity and immunofluorescence techniques to study the antigenic characteristics of human lymphocytes. In an attempt to obtain a reagent specifically reactive with T (thymus-derived) lymphocytes, an antispleen antiserum was absorbed with cellf from five B- (bone marrow-derived) cell lines. After absorption, the antiserum killed 60-75% of peripheral blood lymphocytes and 40-50% of tonsil cells, so that there was a relationship between the percentage of killed cells and the proportion of T lymphocytes. However, when cells after cytotoxic treatment were assayed for rosette formation with sheep erythrocytes (a T-cell marker) 5-20% of viable rosette-forming lymphocytes were found. Therefore, this antiserum was cytotoxic for only 75-90% of T cells. From studies performed with antisera prepared against spleen and B-cell lines, we conclude that lymphoblastoid cells are antigenically different and deficient in comparison to normal B lymphocytes. In addition, cultured B-cell lines appear to be antigenically heterogenous, as shown by the cytotoxic activity remaining in antispleen and anti-B-cell lines sera after absorption with various numbers and types of lymphoid cell lines. After absorption with normal lymphocytes, an antiserum produced against chronic lymphatic leukemia cells had specific activity associated with 12 chronic lymphatic leukemia cells tested. Absorption of the same antiserum with leukemic cells from two patients showed that a certain degree of antigenic heterogeneity also exists among chronic leukemic lymphocytes.

Agammaglobulinemia↗