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K Imai

Publications and source records attributed to K Imai.

At least 1,459 records · Page 81Linked to original sources
PubMed1981

Serological and immunochemical analysis of the specificity of xenoantiserum 8986 elicited with hybrids between human melanoma cells and murine fibroblasts.

Antisera were elicited in rabbits with hybrids derived from the fusion of human melanoma cells with murine fibroblasts. Following absorption with cultured human lymphoid cells, Xenoantiserum 8986 reacts with cultured human melanoma cells and other tumors of nonlymphoid origin. Rosette inhibition assays showed that the xenoantiserum reacts with structures which carry the determinants recognized by the monoclonal antibodies 165.28T and 653.25N and which are recognized by a xenoantiserum elicited with cultured human melanoma cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the immune complexes formed by reacting spent medium of cultured melanoma cells with Xenoantiserum 8986 showed that the antiserum contains antibodies reacting with a M.W. 240,000 melanoma-associated antigen and a M.W. 94,000 melanoma-associated antigen.

Animals↗
PubMed1981

Characterization of monoclonal antibodies to human melanoma-associated antigens.

The hybridomas No. 165.28T, No. 473.54S, and No. 653.25N derived from the fusion of myeloma cells with splenocytes from mice immunized with cultured human melanoma cells secreted monoclonal antibodies recognizing antigenic determinants maximally expressed on cultured human melanoma cells and freshly explanted melanoma cells. Monoclonal antibody No. 376.74T reacted also with carcinoma cell lines but with a significantly lower titer. Rosette inhibition assay showed that these antigenic determinants were expressed on antigenic structures, which are not associated with beta 2 microglobulin and histocompatibility antigens. Two monoclonal antibodies recognized the same or closely associated antigenic determinants, and the remaining two monoclonal antibodies reacted with distinct antigenic determinants. All four monoclonal antibodies could mediate antibody-dependent cellular cytotoxicity of cultured melanoma cells, but none could mediate complement-dependent cytotoxicity.

Animals↗
PubMed1981

Common antigenic determinants on human melanoma, glioma, neuroblastoma, and sarcoma cells defined with monoclonal antibodies.

Antigenic determinants that are common to melanomas, gliomas, neuroblastomas, and sarcomas but that are minimally or not detectably expressed by adult tissues were defined with monoclonal antibodies. Quantitative absorption of monoclonal antibody (Ab 165) with adult tissues followed by testing on antigen-positive UCLA-SO-M14 melanoma cells did not demonstrate antigenic determinant (Ag 165) in brain, lung, liver, kidney, intestine, adrenal, and muscle, Absorption of Ab 376 demonstrated Ag 376 in adult lung but minimal or no antigen in other tissues. Both antigens were associated with a variety of fetal tissues. Assessment of 28 human tumor cell lines with the 131I-staphylococcal Protein A-binding test demonstrated that Ab 165 reacted strongly with melanomas and gliomas and weakly with sarcomas. Ab 376 reacted strongly with melanomas, gliomas, neuroblastomas, and sarcomas. Neither of these antibodies reacted appreciably with carcinoma or teratoma cell lines. Absorption of Ab 165 and Ab 376 with noncultured tumors demonstrated that melanomas, sarcomas, and neuroblastomas can have greater quantities of these antigens in vivo than do normal adult tissues. Qualitative and quantitative antigenic heterogeneity within positive classes of tumors was demonstrated for both cultured and noncultured tumors. The differences in antigen expression in vivo between normal and neoplastic cells suggest potential value for these antibodies in immunodiagnosis and possibly immunotherapy.

Antibodies, Neoplasm↗
PubMed1981

Differential effect of interferon on the expression of tumor-associated antigens and histocompatibility antigens on human melanoma cells: relationship to susceptibility to immune lysis mediated by monoclonal antibodies.

Incubation of cultured human melanoma cells with human leukocyte interferon did not change the expression of melanoma-associated antigens (MAA) recognized by monoclonal antibodies and of Ia-like antigens but significantly increased the expression of HLA-A,B antigens and of beta 2-microglobulin (beta 2-mu). The effect is dependent on the dose of interferon and on the incubation time. Interferon-treated melanoma cells showed an increased susceptibility to lysis mediated by monoclonal antibodies to HLA-A,B antigens and to human beta 2-mu; on the other hand, interferon-treated melanoma cells did not change in their susceptibility to murine natural killer (NK) cell lysis and to immune lysis mediated by monoclonal antibodies to MAA and to Ia-like antigens, and they displayed a reduced susceptibility to human NK cell lysis. Therefore, the increased susceptibility of interferon-treated melanoma cells to lysis mediated by anti HLA-A,B and anti beta 2-mu monoclonal antibodies is likely to reflect the increase in cell surface expression of the corresponding antigens.

Animals↗
PubMed1981

Role of antigen density in immune lysis of interferon-treated human lymphoid cells: analysis with monoclonal antibodies to the HLA-A,B antigenic molecular complex and to Ia-like antigens.

Cultured human lymphoid WI-L2 cells incubated with human leucocyte interferon (final concentration 500 and 2000 U/ml) for 16 h at 37 degrees C acquire increased susceptibility to complement and cell-dependent lysis mediated by monoclonal antibodies to HLA-A,B antigens and to human beta 2-microglobulin but do not change in their susceptibility to immune lysis mediated by monoclonal antibodies to human Ia-like antigens. Changes in susceptibility to immune lysis of interferon-treated lymphoid cells are likely to reflect changes in antigen density, since binding assays with monoclonal antibodies and quantitative absorption assays with alloantisera have shown that the expression of HLA-A,B antigens and beta 2-microglobulin is significantly increased on interferon-treated lymphoid cells, whereas that of Ia-like antigens in not changed.

Antibodies, Monoclonal↗
PubMed1981

HLA-A,B antigens Ia-like antigens, and tumor-associated antigens on prostate carcinoma cell lines: serologic and immunochemical analysis with monoclonal antibodies.

Serologic and immunochemical analysis of the antigenic profile of the 2 human prostate carcinoma cell lines DU-145 and H494 with a battery of monoclonal antibodies has shown that both cell lines express HLA-A,B alloantigens and the 94,000 m.w. tumor-associated glycoprotein recognized by the monoclonal antibody 376.96S. In addition, the cell line H494 unexpectedly expresses Ia-like antigens, which are similar in their antigenic profile and structure to B lymphoid cell derived Ia-like antigens. Both Ia-like antigens and tumor-associated antigens can function as targets of cell-dependent lysis mediated by the corresponding monoclonal antibodies.

Antibodies↗
PubMed1981

Structural properties and tissue distribution of the antigen recognized by the monoclonal antibody 653.40S to human melanoma cells.

The hybridoma 653.40S, constructed with splenocytes from an inbred BALB/c mouse immunized with cultured human melanoma cells, secreted an antibody that had been shown to recognize an antigenic determinant restricted to human melanoma cell lines. The monoclonal antibody (MoAb) 653.40S showed immunoprecipitation of two glycopolypeptides synthesized by melanoma cells, one with the apparent molecular weight of 280,000 and the other one with a molecular weight larger than 500.000. These two glycopolypeptides were not bridged by disulfide bonds and were peripheral rather than integral to the plasma cell membrane. Comparison of the reactivity of cells of the melanocyte lineage with the MoAb 653.40S and with the MoAb Q5/13 to human Ia-like antigens showed that the former reacted with proliferating melanocytes and melanoma cells, whereas the latter reacted only with melanoma cells. The MoAb 653.40S did not react with a large variety of surgically removed normal and tumor tissues except for some instances of basal cell and squamous cell carcinomas. These results suggested that double staining of pigmented skin lesions with the MoAb 653.40S and with an MoAb to Ia-like antigens may help to solve controversial diagnosis of melanoma. Furthermore, the MoAb 653.40S may be useful for radioimaging and immunotherapy of melanoma.

Animals↗
PubMed1981

Human melanoma-associated antigens: role of carbohydrate in shedding and cell surface expression.

The shedding of 2 tumor-specific glycoprotein antigens from human melanoma cells into spent culture medium was selectively inhibited by nontoxic doses (0.5 microgram/ml) of tunicamycin, an inhibitor of N-asparagine-linked glycosylation. The inhibition of shedding of these 2 antigens with m.w. of 240K and 94K is complete within 24 hr after addition of tunicamycin. During this time interval, our data suggest that these glycosylated cell surface antigens are replaced by their nonglycosylated forms. Removal of tunicamycin or addition of N-acetyl glucosamine restores shedding of these melanoma-associated antigens with initially reduced glycosylation. This same selective inhibition of shedding was observed with cultures adapted to grow in high doses (2.5 microgram/ml) of tunicamycin that otherwise killed > 98% of the cells upon first exposure. In contrast to other glycoproteins found in spent culture medium of melanoma cells, the shedding of melanoma-associated antigens is strictly dependent on glycosylation.

Animals↗