Neuraminidase-treated Cells Research Articles

Regeneration of the surface glycoproteins of a transplantable mouse tumor cell after treatment with neuraminidase.

Strain A mouse ascites tumor cells that were treated with neuraminidase (EC 3.2.1.18) (these cells show decreased tumor-forming ability in allogeneic C3H mice) rapidly regenerate sialoglycoproteins at the cell surface during culture. The incorporation of labeled D-glucosamine into membrane glycoproteins of cells that were treated or untreated with neuraminidase proceeds at similar rates. Surface glycoproteins that contain sialic acid are synthesized de novo during culture of neuraminidase-treated cells, and in nondividing cells, synthesis is accompanied by turnover of the membrane glycoproteins. The rate of turnover of membrane glycoproteins that lack sialic acid residues is the same as that occurring in non-dividing cells that are not treated with neuraminidase and that are cultured under identical conditions. Turnover of the surface membrane of nondividing cells leads to the accumulation of glycoproteins in the supernatant medium of cell cultures. The rapid regeneration of cell surfaces that contain sialic acid by TA3 cells that were treated with neuraminidase, makes it unlikely that the rejection of these cells in vivo, in C3H mice, is due solely to the induction of a primary immune response to new or to previously concealed antigenic specificities that would be expressed on the surface of the sialic acid-depleted cell.

Immunotherapy of cancer: immunospecific rejection of tumors in recipients of neuraminidase-treated tumor cells plus BCG.

Firmly established methylcholanthrene fibrosarcomas in syngeneic mice will totally disappear if the hosts are treated with living tumor cells that have been exposed to Vibrio cholerae neuraminidase in vitro. The effect is magnified by the simultanieous injection of a nonspecific immunostimulant, BCG. The rejection of the methylcholanthrene tumor is immunospecific and can be induced only with tumor cells, treated with Vibrio cholerae neuraminidase, identical in type with the growing tumor.

The electrophoretic mobility of normal and leukaemic cells of mice.

1. The pH-mobility relationships for saline-washed cells from a mouse strain of acute lymphoblastic leukaemia were examined before and after treatment with lower aldehydes, diazomethane and neuraminidase (EC 3.2.1.18). 2. The content of sialic acid released into the supernatant fluid of neuraminidase-treated cells was measured. 3. The stability of the charge-determining structures to temporary changes in environment (pH and ionic strength) was established. 4. Similar measurements were made on lymph-node cells obtained from non-leukaemic mice (a resistant and a leukaemia-susceptible strain were examined). 5. It is deduced that both the malignant and the non-malignant cell possess two dissociable acid functions at the cell surface, a carboxyl group of sialic acid and another acidic group(s), probably carboxyl, of pK 3.0-4.5. The malignant cells, however, have a basic dissociable function not present in the non-malignant types. 6. Suggestions are made as to how the difference in surface chemistry may be related to the problem of malignancy.

INTERFERENCE WITH IMMUNE HEMOLYSIS BY GLYCOPROTEIN ANTIGENS.

1. The titer of an individual insulin antiserum measured by hemagglutination agrees favorably with the titer of the same antiserum as measured by immune hemolysis. 2. In contrast, a marked decrease is noted in the immune hemolysis titers relative to hemagglutination titers of antisera prepared against three different sialic acid-containing proteins (human chorionic gonadotropin, rabbit transferrin, and human transferrin). 3. The lower immune hemolytic titers of glycoprotein antisera are apparently not due to a lack of complement-fixing gamma(2)-antibodies. 4. The glycoprotein antigens in solution do not interfere with hemolysis in the insulin immune system. 5. By contrast, marked inhibition of insulin immune hemolysis occurs when cells are sensitized with both glycoprotein and insulin. 6. Cells treated with neuraminidase (to remove cell surface sialic acid) lyse in the presence of C'(a) alone. 7. If neuraminidase-treated cells are sensitized with sialic acid-containing protein, the lysis of these cells by complement is inhibited. 8. It is, therefore, postulated that during some initial phase of immune hemolysis, a sialic acid-containing substrate is cleaved from the cell surface, rendering the cell susceptible to lysis. If this removal is interfered with, i.e., by sensitization of the cell with competitive sialic acid-containing antigen, then the lytic portion of immune hemolysis cannot proceed.

The electrokinetic characterization of the Ehrlich ascites carcinoma cell

The pH-mobility relationships for standard saline washed Ehrlich ascites tumour cells before and after treatment with trypsin, neuraminidase and lower aldehydes have been examined. The supernatant fluids removed from neuraminidase-treated cells have been assayed by the Warren method for sialic acids and the supernatant fluid removed from trypsin-treated cells examined by paper chromatography; these analytical results have been correlated with the electrokinetic data. It is deduced that the surface of the Ehrlich ascites tumour cell examined bears at least three ionogenic systems, a carboxyl group of a sialic acid, which has a p K about 2.8, an unidentified acidic group(s), of p K about 3.5–4.0, and a basic group of p K about 10.