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D B Murphy

Publications and source records attributed to D B Murphy.

At least 109 records · Page 6Linked to original sources
PubMed1981

Immunoregulatory circuits that modulate responsiveness to suppressor cell signal. Failure of B10 mice to respond to suppressor factors can be overcome by quenching the contrasuppressor circuit.

The in vitro antibody response of spleen cells from B10 strain mice is not suppressed by factor preparations made by primed Ly-2 T cells, although these preparations can suppress the in vitro antibody response of spleen cells from other mouse strains (1-3)2. The factor preparations from Ly-2 cells contain at least two separable activities: one that acts as a suppressor moiety (Ly-2 T cell suppressor factor [Ly-2 TsF]) and a second factor that acts as an inducer of contrasuppression (Ly-2 TcsiF); the latter initiates a series of cellular interactions that leads to the inhibition of suppression that we refer to as contrasuppression. Removal of components (either cellular or humoral) of the contrasuppressor circuit makes spleen cells from B10 strain mice as easily suppressible as are those of other mouse strains. Thus, removal of the contrasuppressor inducer cell and/or its biologically active product with the use of an anit-J serum, or removal of the functional acceptor of the inducer cell with the same or other (Ly-2; Qa-1) antisera breaks the B10 suppressor barrier. Contrasuppressive activity. but not helper activity can be eluted from anit-I-J immunoabsorbents. The addition of B10 T cells to either B6 or B10 spleen cell culture deprived of acceptor cells for the TcsiF reconstitutes contrasuppression more efficiently than does the addition of C57BL/6 T cells. Ly-2 TcsiF is more cross-reactive than is Ly-2 TsF so that absorption of factor preparations from sheep erythrocyte-primed Ly-2 cells with horse erythrocytes also breaks the B10 suppressor barrier. The hyperresponsiveness of splenic T cells from B10 strains to Ly-2 TcsiF may be an in vitro exaggeration of a normal in vivo process. Thus it is possible that one can take advantage of this unusual situation to help dissect out the cellular and subcellular components of T cell circuits that moldulate sensitivity to immunoregulatory signals.

Animals↗
PubMed1981

Structure of murine Ia antigens. Two dimensional electrophoretic analyses and high pressure liquid chromatography tryptic peptide maps of products of the I-A and I-E subregions and of an associated invariant polypeptide.

We demonstrate that an invariant polypeptide, first described by Jones et al. (21), co-immunoprecipitates with our Ia molecules, that its interaction with Ia polypeptides varies with haplotype, and that it is not a precursor of the Aalpha, Abeta, Ealpha, or Ebeta. polypeptides. We also show that the polypeptides that we have previously characterized are contaminated with very little, if any, invariant protein. Further, we have used our high-pressure liquid chromatography tryptic peptide map technique to formally map the genes encoding Aalpha, Abeta, and Ebeta to the I-A subregion using recombinant and F1 hybrid mice.

Animals↗
PubMed1981

Immunoregulatory circuits which modulate responsiveness to suppressor cell signals: characterization of an effector cell in the contrasuppressor circuit.

Spleen cells from neonatal animals, placed in culture for 6 days spontaneously develop the ability to block the activity of suppressor T cells, a phenomenon that is referred to as contrasuppression. The effector cell which is derived from the interactions among the cells which comprise a contrasuppressor "circuit" is an Ly-1 T cell. It can be separated from Ly-1 helper cells by three criteria other than function: its generation is dependent on Ly-2+ cells, it is I-J+, and it sticks to the Vicia villosa lectin. Those cells which deliver help to B cells under the experimental conditions studied are not dependent on Ly-2+ cells for generation and neither express determinants that our anti-I-J antisera recognize nor stick to V. villosa. The mechanism by which these Ly-1 contrasuppressor cells function was elucidated by adding them to "'intermediate cultures" containing activated Ly-2 suppressor cells and in vivo immunized Ly-1.1-congenic helper cells. After 48 h in these intermediate cultures, the neonatal Ly-1.2 contrasuppressor cells and the Ly-2 suppressor cells were removed by treatment with the appropriate antiserum plus complement. The remaining activity of the in vivo generated Ly-1.1 helper cells was assayed in fresh cultures of B cells. The contrasuppressor cells not only diminished suppression of the Ly-1 helper cells by the Ly-2 suppressor cells in the intermediate culture, but actually conferred a state of relative resistance to suppression upon the helper cells. This state persisted after the contrasuppressor cells were removed. Why such a cellular circuit, which confers resistance to suppression, might be beneficial to neonatal mice and how considering its attributes might help explain some immunological paradoxes is the subject of discussion.

Animals↗
PubMed1981

Immunoregulatory circuits which modulate responsiveness to suppressor cell signals: contrasuppressor cells can convert an in vivo tolerogenic signal into an immunogenic one.

The intravenous injection of 2,4,6-trinitrophenyl (TNP)-labeled peritoneal exudate cells (TNP-PEC) into CBA mice fails to produce a state of hypersensitivity; rather, it renders recipient mice incapable of mounting a contact hypersensitivity response when they are subsequently immunized with a reactive form of the specific hapten. However, if precultured neonatal spleen cells are injected along with the cells that induce tolerance (TNP-PEC), not only is the development of tolerance inhibited but sensitization to TNP develops. The neonatal spleen cell responsible for turning the tolerogenic signal into an immunogenic one is I-J+ and adheres to the Vicia villosa lectin. Thus, it expresses markers that distinguish contrasuppressor effector cells from helper cells (D. R. Green et al., Eur. J. Immunol. 1981. 11:973), indicating that activated contrasuppressor cells can act as potent, helpful regulatory cells in vivo.

Animals↗
PubMed1981

T cells in a suppressor circuit and non-T:non-B cells bear different I-J determinants.

T cells involved in the generation of suppressor activity bear an I-J-subregion controlled determinant (e.g., J1) which is distinct from that (e.g., J2) found on non-T:non-B accessory cells. T-cell subsets examined include Ly-1 inducer and Ly-1,2 acceptor cells which collaborate to generate suppressor activity in the in vitro sheep red blood cell antibody system. Non-T:non-B accessory cells examined include accessory cells involved in concanavalin-A induced, T-cell proliferative responses and in in vitro antibody responses to sheep red blood cells. These results provide evidence for serologic and genetic complexity of the I-J subregion of the murine H-2 gene complex.

Animals↗
PubMed1981

A non-T:non-B cell bears I-A, I-E, I-J, and Tla (Qa-1?) determinants.

A non-T:non-B accessory cell in peritoneal washout or spleen-cell suspensions facilitates T-cell proliferative responses to the mitogen, concanavalin A. Utilizing monoclonal antibody, we show that this accessory cell bears the same I-A- and I-E-subregion controlled determinants as found on B cells. In addition, the same accessory cell bears a Tla(Qa-1?)-region and an I-J-subregion controlled determinant. This I-J determinant is also present on splenic accessory cells involved in in vitro antibody responses to sheep red blood cells. Data in a companion paper show that not all anti-I-J sera contain antibody reactive with the accessory cell, and suggest that T cells involved in the generation of suppressor activity and accessory cells bear different I-J-subregion controlled determinants.

Animals↗
PubMed1981

Variable synthesis and expression of E alpha and Ae (E beta) Ia polypeptide chains in mice of different H-2 haplotypes.

The genetic and molecular requirements for cell-surface expression of Ia antigens precipitated by anti-I-E subregion sera have been examined. Inbred mice f the d, k, p, and r haplotypes synthesize and express on their lymphocytes the two I-region products normally found in anti-I-E-subregion immunoprecipitates, E alpha and Ae (E beta). Cells from mice of the b and s haplotypes fail to synthesize E alpha chains but do synthesize Ae chains, which remain in the cytoplasm as partially glycosylated precursors. Cells of the f and q haplotypes fail to synthesize either the Ae or E alpha polypeptide chains, as shown by both genetic complementation tests and analyses of total cell proteins by two-dimensional polyacrylamide gel electrophoresis. The patterns of expression of the intact E alpha: Ae complex are consistent with the theory that both the Ae and E alpha polypeptide chains must be present in the cells for either chain to be expressed in normal amounts on the cell surface. The implications of these observations for the genetics of I-region-controlled functions are discussed.

Animals↗
PubMed1980

Monoclonal antibody against an Ir gene product?

Genetic, biochemical, and functional studies have been performed using a monoclonal antibody, Y-17, directed at a conformational or combinatorial determinant formed by certain Ae:E alpha complexes. This determinant appears to be a marker present on a subset of B cells as well as on non-T and non-B spleen cells. Besides Ae and E alpha chains, Y-17 precipitates a third chain that is indistinguishable from the A alpha chain in two-dimensional gels. This results suggests additional combinatorial complexity in the generation of I-region encoded antigens. Y-17 can inhibit the response of T cells to Ae:E alpha determinants in mixed lymphocyte cultures. Furthermore, Y-17 blocks antigen-specific T cell proliferative responses to GLPhe and pigeon cytochrome c which have been shown to require the Ae:E alpha complex as a restriction element for antigen presentation. These results provide strong evidence for the molecular identity of Ia antigens, Ir-gene products and Lad antigens.

Animals↗
PubMed1980

Selective turnover and shedding of H-2K and H-2D antigens is controlled by the major histocompatibility complex. Implications for H-2-restricted recognition.

Lactoperoxidase-catalyzed cell surface radioiodination and incorporation of [3H]-leucine were employed to radiolabel H-2K and H-2D antigens of murine spleen cells. The fate of H-2 antigens was monitored by in vitro culture of labeled cells and isolation of labeled antigens from detergent lysates of the cells and culture supernates obtained at different times during culture. H-2Kk antigens were found to be rapidly turned over and shed by CBA/J cells, whereas the turnover of H-2Dk antigens was extremely slow. Analysis of the membrane residence times of surface-labeled H-2K and H-2D antigens on spleen cells from various H-2-congenic and -recombinant strains demonstrated variations in the shedding rates of H-2K and H-2D antigens, which were controlled by genes mapping in the major histocompatibility complex. These variations show a striking correlation with published, genetically controlled quantitative variations in the cytotoxic response of T lymphocytes to chemically modified or virus-infected syngeneic cells.

Animals↗
PubMed1980

Ly-1 inducer and Ly-1,2 acceptor T cells in the feedback suppression circuit bear an I-J-subregion controlled determinant.

An I-J-subregion controlled determinant is expressed on Ly-1 inducer and Ly-1,2 acceptor T cells in the feedback suppression circuit. Ly-1 T cells absorb the I-J antibody reactive with the Ly-1,2 acceptor T cell, suggesting that both inducer and acceptor T cells have the same I-J determinant. Since less than 10 percent of Ly-1 or Ly-1,2 T cells are killed by anti-I-J plus complement treatment, the I-J determinant demarcates functionally distinct subsets of both the Ly-1 and Ly-1,2 T-cell sets. This I-J determinant is not expressed on a detectable number of Ly-1 helper T cells which induce B lymphocytes to produce anti-sheep red cell antibody in tissue culture.

Animals↗
PubMed1980

Interaction between I region loci influences the expression of a cell surface Ia antigen.

Loci clustered in the I region of the murine H-2 gene complex control the capacity to generate an immune response against foreign antigens (Ir loci) and control differentiation antigens which appear to serve as structures used by cells to interact with and regulate one another (Ia loci). Both genetic and functional studies suggest that Ia antigens may be products of Ir loci. Recent studies have shown that interaction between closely linked Ir loci is required for generating immune responses to certain foreign antigens, and that interaction between H-2-linked loci determines the appearance of an Ia glycoprotein (the Ae chain) on lymphocyte cell surfaces. In this report, we show that one Ia locus regulates the quantitative expression of the product (the E alpha chain) of a second Ia locus. This regulatory locus is dominantly expressed and exerts its effects in either the cis or trans chromosomal position. Thus, the quantitative as well as the qualitative expression of some Ia products is dependent on interaction between tightly linked loci. Our results suggest a possible molecular basis for this regulation: the synthesis and intracellular association of Ae and E alpha chains may be an absolute requirement for the expression of normal levels of either polypeptide chain on the lymphocyte cell surface. The implications these findings have for I region control of immune responses and study of human HLA-D antigens are discussed.

Animals↗
PubMed1980

Identification of microtubule-associated proteins in the meiotic spindle of surf clam oocytes.

Meiotic spindles isolated from surf clam oocytes to morphological purity are biochemically complex, consisting of many polypeptides. These proteins fall into two classes: (a) polypeptides that are apparently cytoplasmic proteins and are not specifically associated with the spindle; and (b) polypeptides that are specifically associated with the spindle. A subset of the spindle-associated proteins, including a 250,000 mol wt component, remain with spindle tubulin through cycles of cold depolymerization and warm polymerization, showing that they are microtubule-associated proteins.

Animals↗
PubMed1980

Ia antigen turnover. II. The kinetics of biosynthesis and release of Ia alpha- and beta-chains by murine spleen cells in culture.

The kinetics of biosynthesis, release, and turnover of Ia antigens were determined by 3H-leucine labeling, immunoprecipitation and SDS-PAGE analysis. Continuous incorporation and pulse-chase experiments demonstrated that the half-life of the total cell Ia pool was 8 hr, with radiolabeled Ia antigens released from the cell within 4 hr of culture initiation. Both Ia alpha- and beta-chains were released by the cells. I-A antigen turnover was more rapid than I-E antigen turnover. However, detailed comparison of I-A and I-E alpha- and beta-chain biosynthesis demonstrated that the E beta (Ae) chains were synthesized more rapidly than E alpha chains, at rates similar to A alpha- and A beta-chains. Once assembled, however, E alpha- and E beta (Ae)- chains were turned over at the same rate. This kinetic anomaly may reflect post-translational association of polypeptides coded by separate genes into complete I-E antigens.

Animals↗
PubMed1979

Recurrent abdominal pain.

A long-term follow-up study (minimum of five years) of 161 children with recurrent abdominal pain disclosed that three had organic disease and that was missed--inflammatory bowel disease. Anorexia nervosa developed in one patient. Three fourths of the patients recovered from the initial symptom; most recovered within a few weeks; but some patients continued to have complaints for a number of years. Approximately 20% of patients underwent additional surgical or medical treatments of doubtful necessity. In 18% of patients, other psychosomatic symptoms developed.

Abdomen↗