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C Hamada

Publications and source records attributed to C Hamada.

At least 73 records · Page 4Linked to original sources
PubMed1981

Close association of virus-specific cell surface and H-2 antigens in Ad12-infected and -transformed mouse cells.

A virus-specific cell surface (S) antigen in adenovirus type 12 (Ad12)-transformed mouse cells has been assumed to be a direct target for cytotoxic thymus derived lymphocytes (CTL). In this study, the spatial proximity between the S and H-2 antigens was determined by three different methods, the proximity and co-capping tests, and the test for blocking of CTL-mediated lysis by anti-H-2 serum. In the proximity test with Ad12-infected thymic and splenic lymphocytes, and an Ad12-transformed line of C3H-He (H-2k) mouse cells, anti-H-2k and anti-S sera reciprocally inhibited fluorescent-antibody staining of the opposite antigens. By contrast, anti-Thy-1, 2 serum as well as anti-Ia and anti-Ig sera failed to show any appreciable effect in this test, when paired with anti-S serum. In addition, the S and H-2 antigens co-capped in the infected thymic lymphocytes, and CTL-mediated lysis of the transformed cells was abrogated equally by treatment of cells with anti-S and anti-H-2 sera. These results clearly demonstrate that there is a close proximity between the S and H-2 antigens on the surface of Ad12-infected and -transformed mouse cells.

Adenoviruses, Human↗
PubMed1979

Tumor-specific transplantation and surface antigen in cells transformed by the adenovirus 12 DNA fragments.

Adenovirus type 12 (Ad 12) tumor-specific transplantation antigen (TSTA) and the surface (S) antigen were examined using rat cells transformed with Ad 12 DNA and its fragments. WY3 (3Yl cells transformed with Ad 12 whole DNA), CYl (3Yl cells transformed with the EcoRI-C fragment of Ad 12 DNA), and GY cells (3Yl cells transformed with the HindIII-G fragment of Ad 12 DNA) contained TSTA and S antigen, but HY cells (3Y1 cells transformed with the BpaI-H fragment of Ad12 DNA) did not. These results suggest that TSTA and S antigens contain a protein(s) coded for by a portion of the transforming gene.

Adenoviridae↗
PubMed1979

Susceptibility of Ad12-transformed S (+) and S (-) mouse cells to cell-mediated immunity in vitro.

Adenovirus type 12 (Ad12)-transformed mouse cells were examined for their susceptibility to cell-mediated immunity in vitro, with respect to the activity of the virus-specific surface (S) antigen in the cells. A transformed cell line, C57AT1, was established from embryonic cells of C57BL/6 mice by Ad12 infection. In fluorescent antibody tests, the transformed cells were positive for the S antigen when the cells were maintained as cultures, whereas when the cells were grown as tumors in animals they became negative for the antigen (referred to as S(+) and S(-) cells, respectively). These S(+) and S(-) cells were subjected to the 51Cr-release test for cell lysis by immune spleen cells (ISC) raised in syngeneic mice by Ad12 infection. When the S(+) cells at various passage levels were exposed to ISC, all of them were lysed extensively and to a similar extent irrespective of their passage history. In contrast, the S(-) cells were consistently refractory to the action of ISC. In addition, the cytotoxic action of ISC was markedly impeded by pretreating the S(+) cells with antiserum to the S antigen, or the ISC with anti-Thy-1,2 serum plus complement. Taken these findings together, the S(+) cells were assumed to be injured by ISC through direct interaction of the S antigen with T-lymphocytes.

Adenoviridae↗
PubMed1976

Inhibition of intracellular multiplication of adenovirus by interaction between infected and uninfected cells.

The possibility that virus multiplication may be inhibited by interaction of infected cells with uninfected cells was tested by experiments, using human adenovirus type 12 (Ad12). Permissive human cells (human embryonic kidney-HEK,KB or HeLa) were infected and seeded on uninfected or infected "nonpermissive" cell (human embryonic lung=HEL) monolayers, and virus yields or proportions of viral antigen-synthesizing cells were compared with each other. Both the virus yields and the proportions of viral antigen-positive cells were not reduced significantly when seeded on infected HEL cells, while they seeded on uninfected HEL cells both of them were reduced remarkably, compared with the yield and the proportion of controls seeded on glass. Similar results were obtained regardless of the type of permissive cells, HEK, KB, or HeLa. Similar reduction of the yield was observed when seeded on HEL cells infected with Ad12 inactivated by heat or by antiserum, and partial reduction was observed when seeded on HEL cells infected with UV-inactivated Ad12, depending on the extent of UV dosis. These experiments showed that intracellular virus multiplication may be inhibited by interaction of infected cells with uninfected cells, and this may be due to the difference in the cell surface structure.

Adenoviruses, Human↗
PubMed1975

Mechanism of induction of cell-mediated immunity to virus infections: in vitro inhibition of intracellular multiplication of mouse adenovirus by immune spleen cells.

Mice were protected from lethal infection with mouse adenovirus (M-Ad) by adoptive transfer of immune spleen cells (ISC) that were prepared from mice immunized with M-Ad and not protected by sonicated ISC. However, a similar extent of protection was also observed by passive immunization with anti-M-Ad serum. In contrast, by in vitro experiments ISC were shown to be able to interrupt intracellular multiplication of M-Ad, whereas sonicated ISC, unimmunized mouse spleen cells, or anti-M-Ad serum were unable to do so. ISC were inhibitory in vitro when added within 12 h postinfection but not when added later. The inhibitory activity of ISC was regarded as due to cell killing by ISC, since the trypan blue exclusion test showed that above 80% of infected cells were killed by ISC even when 5'-fluorodeoxyuridine was added to the cells to block viral deoxyribonucleic acid synthesis, under which conditions control infected cells, to which ISC were not added or normal spleen cells were added, were kept alive at least for a few days. Kinetics studies in M-Ad-infected mice showed that the inhibitory activity of ISC became highest at 1 to 2 weeks postinfection and faded away thereafter in a few weeks, whereas serum antibody titer assayed by passive hemagglutination reached its peak level at about 4 weeks postinfection and declined gradually therafter.

Adenoviridae↗
PubMed1975

One step separation of the sialoprotein possessing ABH and MN blood group activities from human red cell membrane.

Sialoprotein possessing blood group activity has been usually extracted with organic solvents from red cell membrane. To obtain the blood group substance under milder condition, the author presented carboxymethyl (CM) cellulose column chromatography with eluents of phosphate buffer containing 1% Brij 35. Red cell stroma was applied onto the column with an equal volume of 0.0175 M phosphate buffer pH 6.3 and one-fifth volume of 0.05% 2-mercaptoethanol in 1% Brij 35. Separation of the substance was performed by stepwise elution with three kinds of phosphate buffers. Serological assay showed that only the first fraction eluted with 1% Brij 35 in 0.0175 M phosphate buffer pH 6.3 and ABH and MN blood group activities and the other fractions obtained with buffers of higher molarities had not such activities. Sialic acid was also detected only in the first fraction, and the majority of proteins of the stroma was found in the other fractions.

ABO Blood-Group System↗