Induced Resistance to Transmissible Leukemia in Mice

Abstract

MacDowell, Taylor, and Potter 1 present evidence that mice which are naturally susceptible to transplantable leukemia may be rendered insusceptible by treatment with small numbers of leukemic cells. Bashford 2 and others have shown that mice which are naturally susceptible to a transplantable tumor may be immunized by treatment with suspensions of normal mouse cells. The experiments suggested the possibility of rendering susceptible mice refractory to transplantable leukemia by treatment with normal mouse cells.

A strain of transplantable lymphatic leukemia and a group of susceptible mice (AR strain) were obtained through the kindness of Dr. Jacob Furth of the Cornell Medical College. The mouse strain is one which is not abnormally prone to develop spontaneous leukemia. Suspensions of the spleens and lymph nodes of leukemic mice have been passed to normal susceptible mice on an average of once in 6 days. A standard suspension containing about 100,000 cells per mm.³ has been inoculated intravenously in 0.2 cc. amounts. Typical leukemia has resulted in 353 of 360 passage animals, a percentage susceptibility of 98.1.

In Experiment I the effect of treating the susceptible mice with normal mouse cells of another strain which was not susceptible to transplantable leukemia was tested. Twenty-eight susceptible animals were treated on 3 successive days by the intravenous injection of 0.2 cc. of a suspension of minced spleen and lymph-node tissue filtered through cotton from normal mice of the Rockefeller Institute strain. On the fourth day an intraperitoneal injection of 0.5 cc. of similarly prepared material was made. After an interval of 7 days, 11 mice of the group were injected intravenously with 0.2 cc. of a standard suspension of spleen and lymph-node cells from a leukemic mouse of the same strain.