Neuraminidase induced loss in the transplantability of murine leukaemia L 1210, induction of immunoprotection and the transfer of induced immunity to normal DBA-2 mice by serum and peritoneal cells.

Leukaemia L 1210 cells preincubated in vitro with neuraminidase preparations derived either from Vibrio cholerae (VCN) or Clostridium perfringens (CPN) lost their i.p. transplantability for normal DBA/2 mice. This loss of transplantability could not be observed when the enzyme treated cells were implanted in mice whose immune status was suppressed by prior cyclophosphamide treatment. Mice receiving i.p. implants of enzyme treated leukaemia cells developed immunity to subsequent i.p. challenge with untreated L 1210 cells but not to a challenge with Ehrlich ascites tumour cells. The magnitude of immune response evoked by L 1210 cells preincubated with 250 u/ml of VCN or 35 μg/ml of CPN for 60 minutes was of relatively low level when compared with the immunity induced by leukaemia cells preincubated with 50 u/ml of VCN or 15 μg/ml of CPN for 30 or 60 minutes. Evidence is presented to show that the induced immunity can be transferred passively with the serum and with the peritoneal cells from the mice implanted with VCN treated L 1210 cells to normal DBA/2 mice. The significance of the neuraminidase induced increase in the immunogenicity of treated tumour cells is discussed.