Abstract
Although it has been repeatedly attempted, no one has succeeded in transferring immunity to transplantable tumor in animals by injecting the serum of immune animals. Our experiments on passive immunity, duplicating in part the work of others, have also led to negative results, and are recorded simply to add to the existing data.
Serum was obtained from normal rats, from rats immune to inoculations of the Flexner-Jobling rat carcinoma, and from guinea pigs sensitized by three injections of the Flexner-Jobling tumor in doses of 1 gm. These sera were injected daily in doses of 1 c.c. for nine days previous to an inoculation of 0.003 gm. of the Flexner-Jobling tumor, and a control series of non-injected animals was inoculated at the same time, twenty-five animals being used for each series. Four weeks after inoculation, no immunity was demonstrable in any of the treated groups, which showed from 88 to 92 per cent. takes, as compared with 92 per cent. takes in the control groups.
Serum from rats immune to the Flexner-Jobling carcinoma was extracted with chloroform in order to remove the lipoids which, as has been demonstrated by Jobling and his co-workers, inhibit the proteolytic ferments present in that fluid. The lipoid-free serum was injected subcutaneously into a group of 17 rats in doses of I C.C. for seven successive days. Three days after the last injection, these animals and a group of seven controls were inoculated with 0.003 gm. of the Flexner- Jobling rat carcinoma.
Three weeks after inoculation, the animals injected with lipoidfree serum showed 100 per cent. takes as compared with 85 per cent. in the controls. It may be concluded, therefore, that lipoidfree serum, like non-lipoid-free serum, when obtained from immune animals, does not cause passive immunity.
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