Evidence of tumorigenic activity of candidate cell substrates in vaccine production by use of antilymphocyte serum.

Candidate cell substrates for vaccine production must be controlled for the absence of tumorigenic activities. This test is done in most laboratories by heterotransplantation of living cells in Syrian hamsters either subcutaneously into newborns or into the cheek-pouch tissue of older ones. The necessity of a long observation period and high rate of intercurrent mortality among newborn hamsters are the disadvantages of this method. The method described by the authors is based on the use of three-week-old mice. Suspensions of living cells (at least 10(6)) were inoculated simultaneously with an antilymphocyte serum of bovine origin. The application of the antilymphocyte serum is repeated twice. Different heteroploid cell strains were studied and their tumorigenic activities were demonstrated. In no case tumors developed after inoculation of diploid cell strains. The results showed that the use of immunodepressed mice is an efficient method for the determination of the cell culture tumorigenic activity.