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Biomedical subjects

M F Mescher

Publications and source records attributed to M F Mescher.

At least 91 records · Page 5Linked to original sources
PubMed1981

Actin-containing matrix associated with the plasma membrane of murine tumour and lymphoid cells.

A detergent-insoluble matrix has been isolated from murine tumour cell and lymphocyte plasma membranes. The major components of this matrix include actin and four additional proteins not previously identified as cytoskeletal proteins. Labelling studies indicate that the matrix is located on the inner face of the plasma membrane. A cell-surface glycoprotein, 5'-nucleotidase, remains associated with the isolated matrix.

Actins↗
PubMed1981

Cellular interactions in the generation of cytolytic T lymphocyte responses. Analysis of the helper T cell pathway.

Murine splenic lymphocytes exhibit a requirement for helper T cells for the induction of a cytolytic T lymphocyte response to suboptimal doses of allogeneic cells, membranes from allogeneic cells, or purified H-2 antigen in liposomes. The conditions where a requirement for help is apparent are the same conditions where a dependence on splenic adherent cells (SAC) has been demonstrated (Weinberger, O. et al., PROC. Natl. Acad, Sci, USA 1980. 77: 6091). Help can be provided in the form of primed, radioresistant, Ly-1+ spleen or lymph node cells or helper factor (interleukin 2, IL-2). A factor generated from phytohemagglutinin-stimulated human lymphocytes, when added to culture in the presence of antigen, bypassed the requirement for Ia+ SAC and helper cells. IL-2 reconstituted the response to H-2K(k) in liposomes in cultures depleted of SAC, strongly suggesting that the helper cell must see antigen re-expressed by an antigen-presenting cell, whereas the prekiller does not. IL-2 could be generated by culturing Ly-1+ murine spleen cells with H-2K(k) pulsed on SAC.

Animals↗
PubMed1981

Specific reversal of cytolytic T lymphocyte--target cell interaction.

A functional assay is described that measures the reversal of specific cytolytic T cell (CTL)-target cell binding. Binding of 51Cr-labeled P815 cells was stable in suspension but could be readily reversed by the addition of unlabeled P815 cells. The reversal of CTL-tumor cell and CTL-spleen cell binding was H-2 specific; only cells of the same H-2 type as the bound target cell could induce reversal. In all cases, tumor cells were substantially more efficient than spleen cells in inducing specific reversal.

Animals↗
PubMed1981

Lymphocyte recognition of H-2 antigen in liposomes.

Liposomes containing purified H-2Kk will specifically stimulate generation of a secondary allogeneic cytolytic T lymphocyte response. Effective recognition was found to depend on the structure of the liposomes. Including detergent-insoluble plasma membrane matrix during formation resulted in liposomes having two- to fourfold more activity than those prepared using just lipid and H-2.

Animals↗
PubMed1981

Antigen-presenting cell function in induction of helper T cells for cytotoxic T-lymphocyte responses: evidence for antigen processing.

We demonstrate that splenic adherent cells (SACs) play an active role in the presentation of H-2Kk antigen for an alloreactive cytotoxic T-lymphocyte (CTL) response. If antigen is incubated with SACs for 12 hr, they will provide maximal stimulation and present the antigen in the context of their Ia molecules. UV irradiation of these SACs, prior to the 12-hr incubation with H-2Kk antigen, abrogates this stimulatory capacity. Macrophage-bound antigen is not sufficient for stimulation of a response; a second signal is required as well, that, in our system, is provided by phorbol myristic acetate. The SACs are involved in the activation of helper T cells; however, they are not required for presentation of antigen to the precytotoxic T-lymphocyte, which requires two signals for activation, one provided by antigen and the other by a T-cell-derived helper factor.

Animals↗
PubMed1981

Secondary cytolytic T lymphocyte stimulation by purified H-2Kk in liposomes.

Purified H-2Kk incorporated into lipid vesicles induced a secondary allogeneic cytolytic T lymphocyte response. However, the level of the response was much less than that generated by using purified plasma membranes containing an equivalent amount of antigen. Similarly, reconstituted membranes stimulated less effectively than did intact plasma membranes. In both cases the stimulating activity of the antigen was increased by including a detergent-insoluble membrane matrix fraction during formation of the liposomes or reconstructed vesicles. Liposomes formed in the presence of the matrix were larger, were more irregular in shape, and had a higher density than those formed in its absence. Both the H-2 antigen and matrix proteins were incorporated into the same vesicles. The greater antigenicity of H-2 in vesicles containing the matrix protein might be due to either the larger size of the liposomes or interaction of the antigen with a component(s) of the matrix.

Animals↗
PubMed1981

Characterization of an anti-H-2 monoclonal antibody and its use in large-scale antigen purification.

A rat anti-mouse monoclonal antibody (MAb), M1/42, has been found to react with H-2 antigens from cells of the a, b, d, j, k, s, and u haplotypes (all haplotypes tested). This antibody, when bound to cells and reacted with FITC-conjugated anti-rat Ig, could be used to quantitate H-2 expression on several cell types. The antibody was also useful in comparing the H-2 products precipitated from a variety of haplotypes. M1/42-coupled Sepharose-4B beads were used to purify H-2d antigens by affinity chromatography. Pure H-2 molecules eluted from the column in 0.5% DOC, 0.65 M NaCl, 20 mM Tris, pH 8.0, yielding 110 to 180 micrograms H-2d/10(10) P815 tumor cells. This antibody, when used in series with H-2Kk-specific MAb 11-4.1, allowed purification of Dk and Dd from RDM-4 and YAC cells, respectively. H-2d purified by column chromatography on M1/42 was found to be serologically and biologically active, as determined by MAb rebinding, inhibition of cell lysis by alloantisera plus complement and ability to stimulate alloreactive CTL. This antibody and the described protocols should be useful in the preparation of relatively large quantities of a number of H-2 antigens.

Animals↗
PubMed1981

Specific reversal of cytolytic T cell-target cell functional binding is induced by free target cells.

Reversal of specific cell-cell adhesions between allogeneic cytolytic T lymphocytes (CTL) and 51Cr-labeled target cells has been studied by using a functional assay for specific target cell binding. Functional adhesions between CTL and a tumor cell target, the P815 mastocytoma, were stable in suspension for greater than 5 hr. Addition of unlabeled target cells, however, resulted in rapid reversal of functional binding. This reversal appeared to be specific in that no reversal was induced by tumor cells of other H-2 types. Functional reversal of conjugates between CTL and labeled spleen cells syngeneic with P815 also occurred in the presence of unlabeled P815 cells or normal spleen cells of the appropriate H-2 type. The reversal by P815 was substantially more efficient than by normal spleen cells. Furthermore, normal spleen cells of the appropriate H-2 type did not induce reversal of CTL-P815 target conjugates. Purified plasma membranes from P815 cells did not specifically reverse functional binding of CTL to either P815 or normal spleen cell targets. These results demonstrate that functional CTL-target cell binding can be specifically reversed by interaction with free target cells. The rate of reversal appears to be dependent on the relative affinity of the CTL for the bound versus the free target cell. CTL may provide a useful system for studying reversal of specific cell-cell adhesions.

Animals↗
PubMed1981

Kinetics of cytolytic T lymphocyte binding to target cells in suspension.

Cytolytic T lymphocytes (CTL) were able to specifically bind and lyse allogeneic P815 tumor cells and LPS blast cells in suspension. An assay was developed to measure the rate of target cell binding in suspension independent of the rate of lysis. Target cell binding was found to plateau within 3 hr in suspension. The presence of free, functional CTL and targets at these plateaus was demonstrated, indicating that target cell binding was an equilibrium process. Scatchard plots were used to derive values for Kd (apparent affinity) and bmax (maximum binding). Target cell binding in suspension could not be blocked by purified plasma membranes. Target cell binding was compared for CTL generated by secondary in vitro stimulation with intact cells or with purified membranes. These 2 CTL populations yielded distinct values for Kd and bmax. Implications of this kinetic difference for CTL recognition of purified plasma membranes are discussed.

Animals↗
PubMed1980

Cellular interactions in the generation of cytolytic T lymphocyte responses: role of Ia-positive splenic adherent cells in presentation in H-2 antigen.

Splenic adherent cells are required for generation of both primary and, at limiting antigen dose, secondary allogeneic responses of cytolytic T lymphocytes to intact stimulator cells. Secondary responses to purified allogeneic plasma membranes or purified H-2Kk antigens in liposomes are also dependent upon splenic adherent cells. Generation of these responses requires the presence of an Ia-positive. Thy 1,2-negative, radiation-resistant cell in the splenic adherent cell population that is adherent to glass, plastic, and nylon wool. Stimulation of cytolytic T lymphocyte precursors with purified H-2Kk alloantigen bound to Ia+ splenic adherent cells is 10-20 times more efficient than stimulation with antigen added directly to culture. Furthermore, a marked decrease in the response of cytolytic T lymphocytes to liposomes was observed when antiserum against Iad specific for the Ia of the responder cells was added to culture. These results demonstrate that, for purified proteins of the major histocompatibility complex, antigen presentation by Ia+ splenic adherent cells plays a role in the generation of a cytolytic T lymphocyte response.

Animals↗
PubMed1980

Genetic control of murine IgD structural heterogeneity.

Murine B lymphocytes express two native forms of surface IgD: IgDI consists of two delta heavy chains and two light chains; IgDII consists of one heavy chain and one light chain. The relative amounts of IgDI and IgDII present on spleen cells were found to vary significantly among different strains of mice. Genetic evidence demonstrated that the IgDI/IgDII ratio is linked to the Igh-5 allotype. (The delta heavy chain is the product of the Igh-5 locus). Mice bearing the Igh-5e allotype have a low ratio, and mice bearing the Igh-5a or Igh-5b allotype have a high ratio. The Igh-5 locus and the gene controlling the IgDI/IgDII ratio appear to map to the region between the Igh-6 and Igh-V loci.

Animals↗
PubMed1980

Murine cell surface immunoglobulin: two native IgD structures.

Murine spleen cell surface IgD is found in two forms upon SDS-polyacrylamide gel electrophoresis under nonreducing conditions. Both IgDI and IgDII are present on the surface of intact cells and appear to be native structures. Neither form could be accounted for by proteolytic degradation or disulfide bond rearrangement. IgDII has an apparent m.w. of 96,000, suggesting an HL structure. IgDI has an apparent m.w. of 150,000, approximately 33,000 daltons lower than that expected for an H2L2 structure. Significant variation in the relative amounts of IgDI and IgDII was found when mice of different strains were examined.

Animals↗
PubMed1979

Purification of the H-2Kk molecule of the murine major histocompatibility complex.

The intact H-2Kk antigen has been detergent-solubilized and purified using an immunoabsorbent column prepared from the 11-4.1 monoclonal antibody described by Oi et al. (Oi, V. T., Jones, P. P., Goding, J. Current Topics in Microbiology and Immunology (Melchers, F., Potter, M., and Warner, N. L., eds) Vol. 81, pp. 115-129, Springer-Verlag, New York). The mild conditions used for elution from the column, 0.5% deoxycholate in 10 mM Tris buffer, pH 8, with 0.14 M NaCl, result in recovery of 70 to 100% of the allogeneic serological activity. A murine lymphoma, RDM-4, was found to express high levels of H2-Kk; approximately 2 X 10(6) molecules/cell. Milligram quantities of H-2Kk can be purified readily using these cells.

Animals↗
PubMed1979

Murine cell surface immunoglobulin: two forms of delta-heavy chain.

The heavy chain of isolated murine cell surface IgD is present in two forms, separable by electrophoresis on SDS-polyacrylamide gradient gels. Both forms of delta-heavy chain are present on the surface of intact spleen cells and have apparent m.w. of approximately 70,000 (delta1) and 68,000 (delta2). Treatment of surface IgD with neuraminidase before isolation results in a single IgD heavy chain band on SDS gels having an apparent m.w. of 65,000, indicating that delta 1 and delta 2 differ in sialic acid content. Delta 2 is removed from the cell surface by papain more readily than delta 1, suggesting a possible functional significance for the two forms.

Animals↗