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M P Scheid

Publications and source records attributed to M P Scheid.

51 records · Page 3Linked to original sources
PubMed1980

T200 cell surface glycoprotein of the mouse. Polymorphism defined by the Ly-5 system of alloantigens.

The cell line BW5147, and a mutant T200-negative cell line derived from BW5147, were studed by immunoprecipitation and peptide mapping, with xenogeneic monoclonal anti-T200 serum and with Ly-5 alloantiserum. It appears that the Ly-5 system defines a structural polymorphism of the cell surface glycoprotein T200, and that the monoclonal anti-T200 serum defines a feature of T200 that is common to mice of both Ly-5a and Ly-5b genotypes and may be invariable in the species.

Animals↗
PubMed1979

A synthetic pentapeptide with biological activity characteristic of the thymic hormone thymopoietin.

The pentapeptide arginyl-lysyl-aspartyl-valyl-tyrosine, corresponding to amino acid residues 32--36 in thymopoietin, was synthesized. In vitro, this pentapeptide induced the differentiation of murine prothymocytes to thymocytes and inhibited differentiative induction of cells of the B lineage. This combination of actions is presently unique to the parent molecule thymopoietin. In vivo, the pentapeptide reduced the high numbers of autologous rosette-forming cells normally present in the spleens of athymic mice; this also is a property of thymopoietin. These results suggest that this readily synthesized pentapeptide corresponds to an active site of thymopoietin and might serve as a therapeutic substitute for thymopoietin.

Amino Acid Sequence↗
PubMed1979

Disproportion in T-cell subpopulations in immunodeficient mutant hr/hr mice.

Mice of the HRS strain, which carry the mutant gene hr, were examined for abnormalities in representation of the three T-cell sets Ly1, Ly23, and Ly123 in the spleen. The salient feature of hr/hr mice, which are immunologically deficient, in comparison with +/hr segregants, was a gross disproportion in numbers of cells belonging to the Ly1 and Ly123 sets, at the age of 3--3.5 mo. At this age, Ly123 cells of hr/hr spleen outnumbered Ly1 cells by 2:1, whereas in +/hr spleens Ly123 cells were outnumbered by approximately 1:2. Cells from pooled lymph nodes of hr/hr mice did not show a correspondingly gross disporprotion of Ly1 and Ly123 cells. Total counts of splenic T cells, and of B cells, were not significantly different in hr/hr and +/hr mice.

Age Factors↗
PubMed1979

Action of complement in the lysis of mouse sarcoma cells sensitized with H-2 alloantibody.

A modified cytotoxicity assay was adapted from classical erythrocytolytic assays, in which complement components were added in sequence to antibody-sensitized cells. This assay was applied to a model system in which mouse sarcoma cells were sensitized with H-2 alloantibody. The stepwise presentation of complement components combined with the stabilization of C2 by iodine treatment considerably augmented the lytic efficiency of human complement. More generally, the techniques adopted for this study provide a new model for obtaining basic information about selective reaction steps concerned in lysis of nucleated cells by alloantibody and complement. Comparisons of the lysis of sheep erythrocytes by xenoantibody with the lysis of mouse sarcoma cells by H-2 alloantibody, in our assay system with oxidized or untreated human complement, disclosed a difference in the kinetics of C142 formation, manifest in a lag phase and a protracted tmax for the sarcoma cells. These data may suggest that multiple complement-mediated functional lesions are necessary for immune lysis of nucleated cells.

Animals↗
PubMed1978

Immunological studies of mouse decidual cells. I. Membrane markers of decidual cells in the days after implantation.

Mouse decidual cell suspensions from day 6 to day 8 of gestation were prepared by enzymatic treatment with collagenase and trypsin and tested for various membrane markers. (a) Besides H-2 antigens, Thy-1 antigens are present on about 50% of the cells; this may reflect the fibroblastic origin of decidual cells or be a marker expressed on some decidual cells possibly under hormonal control. (b) T or B lymphocytes, as defined by four Lyt antigens or surface immunoglobulins, are not present in significant amounts. (c) A substantial number of cells bearing receptors for the Fc portion of IgG (FcR) is detectable in the decidua, probably closely connected with trophoblast cells; these FcR-bearing cells may act in preventing excessive invasion of uterine tissue by trophoblast or could contribute to the protection of the embryo by interacting with maternal blocking antibodies and trophoblast. No receptors for for complement were detected, even after 16-20 h in culture after trypsin treatment.

Animals↗
PubMed1978

Chemical synthesis of a hexadecapeptide segment of ubiquitin that activates adenylate cyclase and induces lymphocytes to differentiate.

A hexadecapeptide corresponding to positions 59--74 of ubiquitin was synthesized and purified. The peptide was characterized by its mobility in TLC and electrophoresis, amino acid sequence and composition, and molar rotation. The peptide possessed approximately 40% activity compared with native ubiquitin in each of 3 biological assays in vitro: a) thymocyte induction, b) B cell induction and c) elevation of intracellular cyclic AMP levels in sarcoma 180 cells.

Adenylyl Cyclases↗
PubMed1978

The generation and regulation of lymphocyte populations: evidence from differentiative induction systems in vitro.

Results with a dual assay, for the induction of Thy-1+ T cells and of CR+ B cells from marker-negative precursors, confirm that thymopoietin is at present the only known selective inducer of prothymocytes. In contrast, various inducers, including ubiquitin, are active in both assays. Pharmacological evidence indicates that there are different cellular receptors for ubiquitin and thymopoietin. Prothymocytes and pro-CR+ B cells compose two distinct populations in bone marrow and spleen; their distribution in density gradients is different, and elimination of either population enriches the other proportionately. There are no noteworthy differences between induction of these two populations in regard to (a) kinetics, (b) dependence on temperature and protein synthesis, (c) activation by cAMP, and (d) inhibition by cGMP. The opposite inductive effects of cAMP and cGMP were corroborated by the use of pharmacological agents that raise or lower the levels of intracellular cyclic nucleotides. In contrast, a third induction assay, which monitors acquisition of the PC+ surface phenotype, indicates that this differentiative step, the last known for B cells, is initiated by cGMP and inhibited by cAMP. Induction of PC is also inhibited by thymopoietin, signifying that the inductive selectivity of thymopoietin is not due to restriction of its receptors to the T lineage cells. Rather it seems that receptors for thymopoietin occur also on PC-inducible and other B cells, although in this case geared biochemically to inhibition rather than expression of the succeeding gene program. This suggests a role for thymopoietin in the coordinated interregulation of lymphocyte classes, in addition to its better-known function as the thymic inducer of prothymocytes. Present data conform to a general scheme in which the cyclic nucleotides cAMP and cGMP, and agents that affect intracellular levels of these mediators, influence reciprocally the early and late (functional) phases of lymphocyte differentiation as a whole, while thymopoietin influences reciprocally the differentiation of the B and T classes of lymphocyte.

Animals↗
PubMed1975

Chemical synthesis of a peptide fragment of thymopoietin II that induces selective T cell differentiation.

Thymopoietin is a polypeptide hormone of the thymus that consists of a 49 amino acid polypeptide chain of 5562 daltons. A peptide corresponding to positions 29-41 of bovine thymopoietin II was synthesized by the Merrifield solid-phase technique. This peptide was shown to have a purity (correct sequence) of 96% by amino acid and C terminal analyses and by a complete determination of the amino acid sequence by manual Edman degradations. It displayed a selectivity of action similar to that of thymopoietin itself, inducing the differentiation of T lymphocytes but not of complement receptor (CR+) B lymphocytes. Although a number of substances induce the differentiation of both T cells and CR+B cells under the conditions of assay in vitro, only thymopoietin and the synthetic peptide described in this report have been shown to induce the differentiation of T cells selectively. Our data establish that the key residues involved in the active site of thymopoietin are present within a synthetic polypeptide which constitutes a minor portion of the amino acid sequence of thymopoietin. Since this peptide had 3% activity by comparison with thymopoietin, the tertiary structure of thymopoietin may be required for optimal configuration of the active site to produce full biological activity.

Amino Acid Sequence↗
PubMed1975

The ontogeny of murine B lymphocytes. I. Induction of phenotypic conversion of Ia-to Ia+ lymphocytes.

When bone marrow and spleen cells of 4 week-old mice are fractionated on a discontinuous BSA gradient, a small fraction of Ia- cells is obtained which can be induced in vitro to express the Ia alloantigen within 2 hr. This is in precise parallel to the prothymocyte induction system of Komuro and Boyse. Ia specificity is ascertained by the use of two reciprocal antisera, A.TH anti-A.TL (anti-Iak) and A.TL anti-A.TH (anti-Ias), which yield the expected reaction pattern on induced bone marrow cells of (B6 X A)F1 (Iak) and SJL/J (Ias) mice. Induction can be effected by a number of agents, such as catecholamines, prostaglandin PGE1, cAMP, bacterial endotoxin, lipid A, ubiquitin, and thymopoietin. The last requires a 100-fold higher concentration for Ia+ induction as compared to prothymocyte induction, thus implying a lower affinity for the B cell receptor than for the thymocyte receptor. Ia- to Ia+ conversion involves cells different from prothymocytes, as indicated by: 1) the specific cytolytic effect of our anti-Ia sera which were shown to be free of activity against thymocytes; 2) an additive cytolytic effect of anti-Ia and anti-Thy-1 sera; and 3) the fact that the Ia inducible cells are sensitive to pretreatment with anti-immunoglobulin and C. This finding that Ia- precursor cells are already Ig+ is of interest for the B cell ontogeny, as it implies that Ig expression precedes Ia expression.

Animals↗
PubMed1974

Serological crossreactivity between H-Y (male) antigens of mouse and man.

Antisera to H-Y (male-specific) antigen were prepared by immunizing female mice with spleen cells from males of the same inbred strain. These antisera were used in mixed hemadsorption and cytotoxicity tests with cells of rats, guinea pigs, rabbits, and humans. The results showed that the H-Y components of all four species are antigenically related to H-Y of the mouse.

Animals↗