Note on a toxic nucleoprotein obtained from rat carcinoma

Abstract

Flexner-Jobling rat carcinomata of the strain used by Robertson and the author 3 were ground in a mortar with sand, extracted with M/6 NaCl solution, filtered and centrifuged to remove all foreign particles. The supernatant fluid was poured off, diluted with ten times its volume of NaCl solution, and CO₂ allowed to bubble through it for half an hour. A flocculent precipitate which settled in a few hours was the result. Phenol was added to make the suspension 0.5 per cent.

The original problem was to ascertain if such a substance, assumed to be cell globulin, would prove to be specific, using complement fixation as a test. An attempt was made to immunize a rabbit by intravenous injection, but the rabbit died within five minutes after the injection of 3 C.C. (about 50 mgm, dried substance) on the third day. In another rabbit 4 C.C. intravenously proved fatal in ten minutes. In another, 2 C.C. on the first day were without effect, but the following day 2 C.C. caused death promptly. The symptoms are convulsions and cessation of respiration before the heart beat. Immediate post mortem reveals nothing distinctive. In one case there were punctate hemorrhages in the thymus. Others have been negative. There is no intra-vascular clotting, but on the contrary the blood from the heart remains fluid for over an hour.

What has been said of rabbits is also true for white rats, excepting that intra-peritoneal injections make them sick for an hour or so, after which they recover.

As to the substance itself, it is tentatively assumed to be a nucleoprotein. It is weakly positive to the Biuret test, but the color develops slowly. It is negative to the xanthoproteic, positive to the Adamkiewicz and Millon's.