We have learned that the administration of gelatin or its derivatives can induce acquired resistance to Ehrlich's ascites carcinoma transplants 1). Gelatin is a well-known inducer of macrophages. Therefore, the objective of this study was to determine whether the aforementioned immunological phenomenon can be explained solely by macrophage induction, using macrophage inducers other than gelatin, such as peptone, glycogen, and liquid paraffin.

Methods and results

Aliquots (0.3 ml) of porcine skin gelatin, polymerized porcine skin gelatin, acid-polymerized porcine skin gelatin, polypeptone, 1% aqueous solution of glycogen, liquid paraffin, and saline were injected into the inguinal region of mice every 7 days for a total of 5 doses. Seven days after the last injection, 5 x 106 Ehrlich carcinoma cells were subcutaneously transplanted into the lumbar region, and the following results were obtained after 1 month.

Discussion

Of the tested substances known to be macrophage inducers, protein-based substances proved to be effective while sugar- and carbohydrate-based substances were ineffective, suggesting that the aforementioned immunological phenomenon cannot be explained solely by macrophage induction.