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B W McIntyre

Publications and source records attributed to B W McIntyre.

69 records · Page 4Linked to original sources
PubMed1989

Lymphocyte surface antigen L25 is a member of the integrin receptor superfamily.

Monoclonal antibody (mAb) anti-L25 identifies an antigen on the surface of human lymphocytes. This mAb immunoprecipitated three distinct polypeptides of Mr 150,000, 85,000, and 75,000 from Nonidet P-40 lysates of surface radioiodinated lymphocytes. The three polypeptides were found under both nonreducing and reducing conditions. An additional polypeptide of Mr 130,000 was detected in mAb anti-L25 immuno-precipitates when cells were lysed with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate). Epitope localization experiments indicated that both the Mr 150,000 and 85,000 polypeptides contained antibody reactive sites. Peptide mapping studies demonstrated structural similarities in the Mr 150,000 and 85,000 components. The analysis of L25 subunits from lysates of antigen-stimulated T lymphocytes revealed a loss of the Mr 150,000 polypeptides in mAb anti-L25 immunoprecipitates. Solid phase double determinant binding assays demonstrated that L25 is similar and probably identical to lymphocyte surface antigen very late activation-4. This relationship placed L25 as a member of the integrin receptor superfamily.

Antibodies, Monoclonal↗
PubMed1989

Metastatic potential of cloned murine melanoma cells transfected with activated c-Ha-ras.

We sought to determine whether the transfection of tumorigenic but not metastatic cells with the activated c-Ha-ras oncogene was invariably associated with acquisition of the metastatic phenotype. Three clonally derived lines of the K-1735 murine melanoma, characterized as nonmetastatic or poorly metastatic, were transfected with plasmids containing the 6.6-kilobase BamHI fragment of the mutant human c-Ha-ras gene and the neo gene, that confers resistance to neomycin (pSV2neoEJ). Cells transfected with pSV2neo, a plasmid containing the neo gene, served as controls for the procedure of Polybrene-mediated transfection. All cell lines were injected into syngeneic C3H/HeN and into athymic mice, and the results were compared with those produced by highly metastatic K-1735 M-2 cells. Although the pSV2neoEJ-transfected cells produced more rapidly growing s.c. tumors than the control cell lines did, the incidence of spontaneous metastasis was not increased. Following i.v. inoculation, the c-Ha-ras transfectants were retained in lung vasculature in greater proportions than pSV2neo counterpart transfectants were. The c-Ha-ras transfectants also produced significantly more lung tumor colonies, which grew faster than the few lung tumor colonies in mice given injections of control melanoma cells. We concluded that transfection of the activated c-Ha-ras oncogene into nonmetastatic K-1735 melanoma cells leads to accelerated tumor growth in vivo and can confer the ability to form lung colonies after i.v. injection but not the ability to metastasize from a primary s.c. tumor.

Animals↗
PubMed1989

Identification of a murine Peyer's patch--specific lymphocyte homing receptor as an integrin molecule with an alpha chain homologous to human VLA-4 alpha.

Lymphocyte homing is controlled by organ-specific interactions of lymphocytes and high endothelial venules (HEV). Adhesion of lymphocytes to Peyer's patch HEV, but not to peripheral node HEV, is inhibited by an antibody recognizing the murine lymphocyte antigen LPAM-1. Lymphoma cell variants were selected on the FACS for differences in LPAM-1 expression: the binding capacity of these variants to Peyer's patch HEV directly correlates with the level of LPAM-1 expression. The anti-LPAM-1 antibody recognizes the alpha subunit of an Mr 160,000/130,000 cell surface alpha beta heterodimer. The association of LPAM-1 alpha and beta chains requires the presence of Ca2+ ions. Proteins of Mr 84,000 and Mr 62,000 present in LPAM-1 immunoprecipitates appear to be products of the proteolytic processing of alpha chains. The structure of LPAM-1 is virtually identical to that of the human integrin receptor VLA-4. The cross-reactivity of a monospecific rabbit antiserum demonstrated the similarity between the human VLA-4 alpha chain and the alpha subunit of LPAM-1.

Animals↗
PubMed1989

Generation of antigenic variants from a nonantigenic murine tumor cell line by transfection with a gene encoding a novel tumor-specific transplantation antigen.

Tumors induced in mice by UV radiation often express highly immunogenic tumor-specific transplantation antigens (TSTA). The 216 gene, which encodes a TSTA of the C3H tumor UV-1591, has been cloned and characterized as a novel major histocompatibility complex Class I antigen. The purpose of this study was to determine whether the 216 gene-encoded TSTA can function as a tumor rejection antigen when expressed on unrelated, nonantigenic murine tumor cells or whether its function is restricted to UV-induced tumors. A cell line (10T-1) derived from a spontaneous transformant of C3H 10T1/2 cells was cotransfected with DNA from p216 and pSV2-neo plasmids. About 2 wk after transfection, G418-resistant colonies were isolated randomly and tested for cell surface expression of the 216 gene product using a monoclonal antibody specific for 216 gene-encoded TSTA. Of 20 clones tested, four expressed high levels of 216 gene-encoded TSTA. These four clones were highly antigenic in that they were completely rejected in normal mice but grew progressively in nude mice. Furthermore, the 216-positive clones were immunologically cross-reactive with UV-1591, as determined by in vitro cytotoxic T-lymphocyte and in vivo immunization and challenge assays. Surprisingly, 216-positive 10T-1 transfectants also cross-reacted with 10T-1 cells, both in vitro and in vivo. These results demonstrate that the product of a cloned TSTA gene from a UV-induced murine tumor is capable of functioning as a tumor rejection antigen when expressed on unrelated, nonantigenic tumor cells. In addition, these results indicate that this approach could be used to augment the immune response against poorly antigenic tumors.

Animals↗
PubMed1989

Characterization of env gene recombination in x-ray--induced thymomas of C57BL/6 mice.

A role for specific recombination events at the env region of endogenous murine leukemia virus (MuLV) sequences in radiation carcinogenesis in C57BL mice has been suggested by a number of studies. We characterized env-related cell surface antigens from a primary, x-ray--induced, and several transplanted C57BL/6 thymomas of viral and radiation etiologies by immunoprecipitation and two-dimensional peptide mapping. DNA from lymphoma cells was also analyzed by Southern blotting for evidence of mink cell focus-forming (MCF) type env recombination events. Although gp70 molecules with novel structural determinants were found on all transplanted lymphomas examined, expression of novel env antigens was variable among these lymphomas, and there was a lack of correlation of characteristic MCF-type env recombination events in endogenous retrovirus DNA sequences with novel env antigens on lymphoma cell surfaces. Neither novel gp70 antigens nor MCF-type env provirus recombinant structures were consistent features of the C57BL/6 thymomas of radiation etiology examined in this study, even though MCF-type env recombination events have been suggested as etiologically significant in MuLV-mediated lymphomagenesis in both RadLV and x-ray--induced tumors in C57BL/6 mice.

Animals↗
PubMed1987

Identification and characterization of two novel lymphocyte function-associated antigens, L24 and L25.

We describe the function and cell distribution of two novel cell surface antigens, L24 and L25. These antigens are broadly distributed on human lymphocytes. Monoclonal antibodies specific for these molecules block lysis by Class I- and II-specific cytotoxic T lymphocytes, but do not affect any other T cell functions tested. Anti-L24 antibody immunoprecipitates a molecule composed of two disulfide-linked monomers of 140 kd each. Anti-L25 antibody immunoprecipitates three proteins of 150, 85, and 75 kd. The study of these and other function associated molecules may provide insight into mechanisms of cytotoxic T lymphocyte recognition and/or function.

Antibodies, Monoclonal↗
PubMed1986

The congenic mutant B6.C-H-2bm-1 (H-2bm-1) serological response to the T-cell receptor on EL4.

Antisera reactive with the C57Bl lymphoma EL4 were induced by hyperimmunization of B6.C-H-2bm-1 (H-2bm-1) mice, a congenic mutant strain of C57Bl/6 (B6). Molecular weight determinations of EL4 surface structures detected with the congenic mutant antibodies were accomplished by electrophoretic analyses (one and two dimensions) on sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE). Analysis of immunoprecipitates in the first dimension under reducing conditions revealed protein bands corresponding to gp 70 and its 33-kDa cleavage fragment, and two-three bands (40-45 kDa) that overlapped with those precipitated from EL4 with AS 8177, an antiserum which detects framework determinants on the T-cell heterodimeric receptor. Further analysis by diagonal electrophoresis confirmed identity of the 40- to 45-kDa proteins precipitated from EL4 with either AS 8177 or H-2bm-1 anti-EL4 sera. Additional diagonal electrophoretic studies showed that the congenic mutant antibodies do not precipitate T-cell receptor molecules from C6VL, an in vitro line derived from the C6XL T-cell lymphoma of C57Bl/ka origin, which was previously shown by some of us to express the heterodimeric T-cell receptor. Together these results demonstrate detection of the heterodimeric T-cell receptor on EL4 with congenic mutant antibodies directed against nonconstant region determinant(s), and indicate a possible linkage between MHC haplotype and the immune response to intraspecies variable regions of the T-cell receptor.

Animals↗
PubMed1985

Molecular characterization of the murine T cell antigen receptor and associated structures.

Previous studies have demonstrated that the T cell antigen-specific receptor is a disulfide-linked heterodimer with subunits of 40-48 kilodaltons. We have produced a series of antiserums and monoclonal antibodies to epitopes carried by the molecule, including clonotypic epitopes specific to individual T lymphomas as well as epitopes shared by different T cell lines. Using these reagents we have isolated the heterodimers from a variety of T cells for comparison of primary structure via two-dimensional peptide mapping. The results indicate that the peptide maps of the alpha and beta subunits are extremely different, indicating that the subunits are encoded by different genes, and both subunits contain constant as well as variable peptides. To determine whether the murine T cell receptor is associated with other cell surface structures, C6VL lymphoma cells were radioiodinated, cross-linked with the cleavable reagent dimethyl-3,3'-dithiobispropionimidate, solubilized, and subjected to immunoprecipitation with the clonotypic antibody 124-40, and the precipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cross-linked samples, but not sham-treated precipitates, contained structures similar to the human Leu-4/T3 structure in addition to the receptor subunits. These results indicate that similar structures may be associated with the receptor in the human and the mouse.

Amino Acid Sequence↗
PubMed1984

Biosynthesis and processing of murine T-cell antigen receptor.

The antigen-specific receptor of C6VL T-lymphoma cells is a disulfide-linked heterodimer composed of 39 kd alpha chain and a 41 kd beta chain, both of which exhibit charge microheterogeneity. Pulse-chase labeling experiments indicate that epitopes reactive with the anti-receptor xenoantiserum #8177 were detectable by 2 min, while the clonotypic epitope reactive with monoclonal antibody 124-40 was not detectable until 10 min. Digestion with endoglycosidases H and F revealed that both subunits have at least three N-linked oligosaccharide side chains. The deglycosylated alpha and beta subunits were 27 and 32 kd, respectively. These data suggest that the dimeric receptor is formed shortly after translation, followed by extensive glycosylation. Emergence of the C6VL clonotypic epitope, and perhaps the antigen binding site, may therefore be dependent on post-assembly events.

Animals↗
PubMed1984

The murine T cell antigen receptor and associated structures.

The immunochemical approach described in this review has led to the identification of a new component of the T cell surface, the disulfide-linked heterodimer, which has many of the properties expected of a molecule with antigen-specific receptor activity: 1) Expression of the heterodimer is restricted to T cells. 2) The molecule expresses clonotypic epitopes presumably related to the specific antigen recognition site, as well as crossreactive epitopes associated with the molecular framework. 3) At the primary sequence level, the molecule has regions of constant as well as variable structure. The numerous observations from other laboratories that clonotypic antibodies which inhibit antigen-specific reactions are directed against similar disulfide-linked heterodimers provide compelling evidence that this structure is in fact the T cell antigen receptor. Two important conclusions can be drawn from the results of peptide analysis of the receptor subunits. First, the molecular fingerprints of the alpha and beta chains are very different, indicating that the subunits are encoded by different genes. Second, both subunits have constant and variable regions, suggesting that both subunits play a role in producing the antigen combining site. A crucial question that remains to be answered is whether the same or different combining sites are responsible for recognition of antigen and the MHC restricting element. The recent report by Marrack et al. (1983b) that the receptors of two independent T cell hybridomas with the same antigen and MHC specificities expressed the same clonotypic determinant and yielded identical peptide maps (Kappler et al. 1983) provides strong evidence that the heterodimer is responsible for both antigen and MHC recognition. If this is the case, it remains to be determined whether a single site contributed by both subunits recognizes antigen and MHC, or whether one subunit contributes a site for MHC recognition and the other a site for antigen recognition. If, however, as Parham (1984) has recently proposed, conserved rather than polymorphic regions of the MHC product are recognized in MHC restriction, it is possible that the heterodimer functions solely in recognition of antigen, and the restriction may be provided by accessory proteins in a receptor complex. Definitive conclusions as to the role of the individual chains will probably require construction of functional T cells using molecular clones of the genes encoding the receptor and accessory proteins. Recently, the molecular cloning of cDNA encoding putative T cell receptors has been reported from murine (Hedrick et al. 1984) and human (Yanagi et al. 1984) cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Immunochemical characterization of differentiation and age-related cell surface antigens expressed by chicken erythrocytes.

Hematopoietic-lymphoid membrane antigens that are related to cell differentiation and development, referred to as chicken fetal antigen (CFA) and chicken adult antigen (CAA) were immunochemically characterized; Mr 220,000; Mr 170,000; Mr 130,000; Mr 99,000; Mr 88,000; Mr 50,000; and Mr 24,000 CFA molecules are detected on embryonic RBC, and Mr 210,000; Mr 130,000; Mr 102,000; Mr 56,000; Mr 48,000; and Mr 43,000 CAA molecules are detected on adult RBC. Limited peptide mapping analyses showed all of the CFA and CAA molecules to be distinct entities. Both the Mr 50,000 CFA and the Mr 43,000 CAA molecules exhibited multiple isomorphic variants when analyzed by 2-dimensional electrophoresis. Analyses involving neuraminidase treatments and limited peptide mapping showed the Mr 50,000 CFA isomorphic variants to be chemically identical with the isoelectric point variations being due to sialic acid differences. In addition to multiple isomorphic variants, the molecular weight and charge differences of which were diminished by neuraminidase treatments, the Mr 43,000 CAA molecules exhibited a doublet pattern suggesting that the polyclonal antisera may be detecting chicken major histocompatibility complex products. Analyses of the Mr 50,000 CFA molecules immunoprecipitated with monoclonal antibody 190-4 confirmed that the monoclonal antibody recognizes a serological subset of the Mr 50,000 CFA molecules but showed that it did not recognize a unique molecularly detectable subset among the 18 isomorphic variants discernable by 2-dimensional electrophoretic analyses. Cocapping analyses with splenic lymphocytes showed CFA and CAA to occur as distinct membrane entities on lymphocytes.

Animals↗
PubMed1983

The mouse T cell receptor: structural heterogeneity of molecules of normal T cells defined by xenoantiserum.

We have previously demonstrated that T lymphomas may express clonally specific epitopes that are carried by a T-cell-restricted, disulfide-bonded heterodimeric glycoprotein. We have used a monoclonal antibody, 124-40, to isolate the lymphoma-specific antigen and raise a xenoantiserum to the molecule. This antiserum immunoprecipitates a family of disulfide-bonded dimers from normal thymocytes and T cells, but is unreactive with B cells. Peptide maps prepared after limited proteolytic digestion indicate that the molecules from the different cell populations have homologous primary structures. Comparison of two-dimensional tryptic peptide maps indicate that, in addition to several common peptides, the molecules exhibit considerable structural heterogeneity. Taken together, these data indicate that the T-cell-specific heteroduplex has regions of constant and variable structure consistent with the properties expected for the T cell antigen receptor.

Amino Acid Sequence↗
PubMed1982

Tumor-specific antigen of murine T-lymphoma defined with monoclonal antibody.

A panel of hybridomas was constructed by fusion of P3X63Ag8 myeloma cells with spleen cells from a BALB/c mouse that had been immunized with a C57BL/Ka x-ray-induced lymphoma, C6XL. One of forty-three hybridomas secreting antibodies reactive with the tumor cells was found to be unreactive with normal spleen cells in a radioimmunometric assay. This antibody, designated 124-40, was unreactive with normal adult thymus, spleen, lymph node, or bone marrow cells, or with fetal spleen or thymus cells in radioimmunometric or radioimmunoprecipitation assays. Flow microfluorometric analysis of these nonmalignant lymphoid cells failed to reveal subpopulations reactive with MAb 124-40. The antibody was highly specific for the lymphoma cells used for immunization and did not react with a panel of other spontaneous or x-ray-induced or chemically induced lymphomas. The antigen reactive with MAb 124-40 was isolated by radioimmunoprecipitation and found to be a glycoprotein composed of disulfide-bonded subunits of 39,000 m.w. and 41,000 m.w. A cell surface component of similar structure, but not reactive with MAb 124-40 could be detected by two-dimensional electrophoresis in extracts of purified T cells, but not B cells. These results suggest that the apparently individually specific lymphoma antigen reactive with MAb 124-40 might be a clonally expressed epitope carried by a T cell surface component.

Animals↗
PubMedDate not supplied

Non-random primary and secondary chromosomal abnormalities in human gastric cancers.

By using Giemsa-banding and fluorescence in situ hybridization techniques, we have been able to identify primary and secondary cytogenetic abnormalities in four gastric tumors at different stages of development. Structural and numerical abnormalities were present in all four gastric tumors in chromosomes 3, 7, 11, and X. Other abnormalities involving chromosomes 1, 5, 6, 8, 13, 15, 17, 18, 19 and 22 were observed, but only in three advanced gastric tumors, suggesting that these were secondary/tertiary genetic defects. Based on these results it was possible for us to decipher primary and secondary genetic abnormalities in these four gastric tumors.

Biopsy↗