Susceptibility of Newborn Mice of an Otherwise Apparently “Resistant” Strain to Inoculation with Leukemia. ∗

Summary

1. A strain of transplantable lymphatic leukemia which originated in a mouse of the Ak line was found to be highly pathogenic for suckling infants of the C3H inbred line. Cell suspensions (20%) prepared from liver, spleen and lymph glands of leukemic mice of the Ak line, reproduced acute leukemia within 12 days when inoculated under the skin (0.05 cc) of newly born suckling mice of the C3H line.

2. This striking susceptibility of suckling C3H infants to inoculation with Ak leukemia appears to be limited to their first few days of life. Practically all infants of the C3H line (82 out of 85) developed leukemia when inoculated within the first 7 days of life; only 27 out of 57, however, were found to be susceptible when inoculated at ages varying from 8 to 15 days. Of 60 infants, 16 to 30 days old, only 15 reacted to inoculation.

3. Forty-nine adult mice of the C3H line were inoculated subcutaneously and 9 intraperitoneally with large doses (0.2 to 1 cc) of Ak leukemia and none reacted. When, however, overwhelming doses (3 cc each) of the Ak leukemic cell suspension were injected into adult mice of the C3H line, 1 out of 5 inoculated subcutaneously, and all 6 inoculated intraperitoneally died from leukemia.