Search PubMed⌕ Search

Biomedical subjects

E S Vitetta

Publications and source records attributed to E S Vitetta.

At least 325 records · Page 18Linked to original sources
PubMed1975

Studies on the murine Ss protein. I. Purification, molecular weight, and subunit structure.

The murine Ss protein has been isolated and purified. Using specific antisera, the radiolabeled protein has a mol wt of 120,000 in sodium dodecyl sulfate polyacrylamide gels. It is composed of two basic subunits of 23,000 and 14,000 daltons. The smaller molecular weight subunit contains a single disulfide bridge, is devoid of carbohydrate, and may represent the murine equivalent of beta2-microglobulin.

Amino Acid Sequence↗
PubMed1975

Expression of murine leukemia virus envelope glycoprotein gp69/71 on mouse thymocytes. Evidence for two structural variants distinguished by presence vs. absence of GIX antigen.

Thymocytes of several mouse strains were tested for expression of the gp69/71 envelope component of murine leukemia virus by surface iodination, followed by immunoprecipitation and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Theses strains included two congenic lines differing from their partner stocks with respect to expression of GIX antigen demonstrable in the cytoxicity assay. We conclude that:(a) two structural variants of gp69/71 can be expressed on mouse thymocytes, (b) these are distinguishable by a small difference in mobility in SDS gels, (c) one carries GIX antigen and the other not, (d) they are coded, or their expression is regulated, by different chromosomal loci that are not closely linked, and (e) both can be expressed together on the thymocytes of inbred mice. In the intact thymocyte plasma membrane, the sites of group-specific antigen shared by the two gp69/71 variants, unlike the GIX type specificity carried by only one of them, are probably inaccessible to antibody.

Alleles↗
PubMed1975

Biochemical evidence linking the GIX thymocyte surface antigen to the gp69/71 envelope glycoprotein of murine leukemia virus.

It is known that the thymocyte surface antigen GIX is found in some strains of mice and not others, and that its expression in mice of strain 129, in which most extensive genetic studies have been made, is controlled by two unlinked cellular chromosomal loci. We have now isolated a protein with a mol wt of approximately 70,000 daltons from the surface of thymocytes from 129 mice, which have antigenic and biochemical properties characteristic of the gp69/71 envelope component of murine leukemia virus. Our evidence is compatible with the conclusion that it carries the GIX antigen.

Animals↗
PubMed1975

Cell surface immunoglobulin. XI. The appearance of an IgD-like molecule on murine lymphoid cells during ontogeny.

An Ig molecule containing L chains and H chains similar to human delta-chains has been detected on the surface of radioiodinated murine lymphoid cells. Newborn mice have only IgM on their splenocytes. Between 10 and 15 days, the IgD-like molecule appears and increases in amount until 3 mo of age, when it is the predominant cell surface Ig in terms of radioactivity. IgD is found only in peripheral lymphoid tissues and is present in larger amounts on peripheral lymph node cells (approximately 85% of surface Ig) than on splenocytes (approximately 50%). IgD is also present in comparable amounts on cells from both nu/nu and germfree mice, indicating that its expression may be independent of both thymic influence and antigenic stimulation. These studies suggest that there is a switch from cell surface IgM to IgD that occurs during differentiation of virgin B lymphocytes in the spleen.

Age Factors↗
PubMed1975

Guinea pig immune response-related histocompatibility antigens. Partial characterization and distribution.

We have previously demonstrated that guinea pig alloantisera directed at strain 2 and strain 13 membrane antigens block specific lymphocyte activation in immune response gene-controlled systems. In this communication we describe the partial characterization of the antigens against which these antisera are directed (the 2 and 13 antigens) and, in addition, that of the B antigen which by distribution resembles the human HL-A and mouse H-2 major histocompatibility antigens. Lymphoid cells from strain 2 and strain 13 guinea pigs were surface labeled with 125I by the lactoperoxidase technique. Nonidet P-40 extracts of these labeled cells were precipitated by sandwiches of strain 2 antistrain 13, strain 13 antistrain 2, or outbred anti-B antisera, followed by rabbit antiguinea pig immunoglobulin antisera. Precipitates were dissolved in sodium dodecyl sulfate (SDS) and electrophoresed on SDS polyacrylamide gels. Radioactive peaks representing the 2 and B-cell membrane antigens were obtained from strain 2 lymph node cells, as well as from a B-lymphoid cell population (L2C leukemia cells) and a T-lymphocyte population (STRAIN 2 PERITONEAL EXUDATE LYMPHOCYTES [PELs]). Radioactive peaks representing the 13 and B-cell membrane antigens were obtained from strain 13 lymph node cells and strain 13 PELs. All anti-B precipitates produced two peaks when electrophoresed on SDS polyacrylamide gels; one representing an antigen with a mol wt of approximately 45,000, and one representing an antigen with a mol wt of about 12,000. Both may be components of a single protein. All anti-2 and anti-13 precipitates produced a single peak when electrophoresed on SDS polyacrylamide gels. Both the 2 and 13 antigens were found by this technique to have mol wt of approximately 25,000. By molecular weight criteria, as well as by previously investigated distributional criteria, the B antigen is similar to the human LA and Four antigens, and to the mouse D and K antigens, and the 2 and 13 antigens are similar to the mouse Ia antigens.

Animals↗
PubMed1975

Cell surface immunoglobulin. XII. Localization of immunoglobulin on murine lymphocytes by scanning immunoelectromicroscopy.

The localization of immunoglobulin (Ig) on the surface of murine splenic lymphocytes has been studied with the scanning electron microscope (SEM), using a rabbit F(ab')2 hybrid antibody directed against mouse Ig and tobacco mosaic virus (TMV) with TMV as a morphological marker. 35% of spleen cells and 3% of thymus cells were labeled by this method. Labeled cells were usually small lymphocytes with moderate numbers of microvilli. The Ig molecules were randomly distributed on the lymphocyte surface, appearing on microvilli as well as on the smooth surface of the cell.

Animals↗
PubMed1975

Structural similarities between a product of the T/t-locus isolated from sperm and teratoma cells, and H-2 antigens isolated from splenocytes.

Molecules specified by the H-2-linked T/t locus in the mouse are expressed on H-2-negative cells such as early embryos, sperm, and teratoma cells. By means of enzymatic radioiodination of cells and immunoprecipitation of lysates with congenic antiserum, one of these molecules, known as F9, has been obtained from sperm and teratoma cells and compared to H-2 isolated from murine splenocytes. Our studies indicate that both H-2 and F9 have identical molecular weights and subunit structure, including the presence of a B2-microglobulin-like subunit. These findings, taken together with previous studies of TL alloantigens, suggest that a number of gene products of the 9th linkage group show structural homology with each other and, in addition, with immunoglobulin. The genes in question may therefore have arisen from a primitive gene concerned with cellular recognition.

Animals↗
PubMed1975

Absence of H-2 antigens capable of reacting with cytotoxic T cells on a teratoma line expressing a T/t locus antigen.

An established cell line of murine teratoma cells (F9), which lacks serologically detectable H-2 that is determined by a wild-type T/t locus gene. These cells are not killed and do not react with cytotoxic T cells sensitized to H-2 antigens in a cell-mediated lympholysis assay. Modification of spleen cells from the strain or origin (129) of this teratoma line with trinitrobenzene sulfonic acid allows the generation of syngeneic killer cells that display a cytotoxic effect against trinitrophenyl-modified splenic targets, but not against trinitrophenyl-modified F9 targets. Thus, the F9 antigen is structurally similar to H-2b but does not act as a target antigen in the cell-mediated lympholysis assay for anti-H-2b cytotoxic T cells, nor does it crossreact with H-2b antigens at the T cell level.

Animals↗
PubMed1975

Synthesis of surface H-2 alloantigens in murine splenocytes.

The synthesis and turnover of cell surface H-2 alloantigens were studied in murine splenocytes by the anti-H-2-bind method to separate precursor-labeled surface from intracellular molecules. Results indicate that newly synthesized H-2 antigen, labeled in either its peptide or carbohydrate portion enters a relatively small pool of intracellular H-2 antigen and then is rapidly transported to the plasma membrane which represents a larger compartment. The simplest interpretation of these findings is that H-2 antigen is synthesized and transported along a conventional secretory pathway. Pulse-chase experiments indicate that H-2 antigens are not readily chased from the plasma membrane and are not shed or internalized during short-term culture. The aforementioned observations are discussed in terms of a cellular heterogeneity.

Animals↗
PubMed1975

Anti-receptor antibody. I. Isolation and characterization of the immunoglobulin receptor for phosphorylcholine.

We have demonstrated a phosphorylcholine-binding protein in lysates from radioiodinated splenocytes of immunized mice. Immunoprecipitation with anti-receptor antibody of lysates from splenocytes obtained from animals undergoing a primary response or from mice immunized 4 to 6 months earlier with antigen demonstrated that this protein contained H and L chains. Therefore, we have isolated an antigen-specific receptor from the surface of spleen cells from both immunized and "memory" animals. This receptor Ig comprises approximately 10% of total cell surface Ig.

Animals↗
PubMed1975

Cell surface immunoglobulin. XIII. Distribution of IgM and IgD-like molecules on small and large cells of mouse spleen.

The distribution among murine spleen cells of a newly described class of surface immunoglobulin (Ig) with properties similar to human IgD was studied. Splenocytes were separated on the basis of size and the surface Ig on large cells (sedimenting faster than 6 mm/hr in a 1 times G velocity gradient) and small cells (sedimenting between 2.5 and 3.0 mm/hr) was analyzed. Spleen cells from young animals had virtually only IgM on the large cells but had substantial amounts of IgM and the IgD-like molecule (IgD) on small cells. Spleen cells from older animals, which have larger amounts of IgD, had IgM and IgD on both cell types; however, the amount of IgD relative to IgM on the large cells was always substantially less than that on the small ones. These observations taken together with those of other investigators support the hypothesis that a large lymphocyte with surface IgM is the precursor of a small lymphocyte with both surface IgM and IgD.

Animals↗
PubMed1974

Cell surface immunoglobulin. IX. A new method for the study of synthesis, intracellular transport, and exteriorization in murine splenocytes.

A new method for the detection of cell surface immunoglobulin labeled with isotopic precursors is described. The method consists of the aggregation of surface Ig on cells with specific antibody (heterologous) and the subsequent removal of antigen-antibody complexes by the combination of high speed centrifugation and immunoprecipitation of remaining soluble complexes using antibody to the heterologous Ig. Using this method, the kinetics of appearance of cell surface Ig and its turnover were studied in murine splenocytes. The results suggest that cell surface Ig is synthesized and transported in the same manner as secretory Ig rather than being synthesized on the plasma membrane. The turnover of intracellular and cell surface Ig in lymphocytes is slow. In contrast, intracellular Ig in plasma cells is rapidly secreted and usually without a cell surface phase. Cell surface Ig was shown to be radiolabeled with [(3)H]glucosamine, -galactose, and -fucose. The proportion of cell surface to intracellular (nonsurface) Ig labeled with these precursors suggests the same sequence of addition of sugars to Ig destined to be on the surface of lymphocytes as with Ig which will be secreted by plasma cells. Results with this new method also confirm earlier conclusions based on experiments using cell surface iodination: 8S IgM is the predominant Ig on the surface of murine splenocytes and the molecule appears to be attached by its micro-chains.

Animals↗