Induced immunologic response to tumors.

A tumoricidal system has been described utilizing a two-step process which, first, specifically alters the antigenic nature of a tumor cell and, second, adds a heterologous cytotoxic anti body without affecting normal cells. The antigenic structure of the tumor cell is altered by the nitrogen mustard, L-phenylalanine mustard, and a specific antibody is made to this mustard by injecting it into the rabbit as a hapten conjugated to human gamma-globulin. Selectivity in the system concen trating the hapten and later the specific antibody on the tumor cell is obtained by utilizing the loss of selective permeability in the tumor vessels. L-phenylalanine mustard is introduced intravenously as a primary injection followed in a half-hour by an intravenous injection of the antibody. The system has been demonstrated to be tumoricidal but, as yet, has low efficiency and high toxicity.