Comparative studies of subcutaneous and intradermal leukemic tumors in guinea pigs.

Abstract

Summary Small doses of L2C leukemic cell suspensions inoculated intradermally into strain 2 and F 1 hybrid guinea pigs induced leukemic tumors that regressed spontaneously in about 50% of animals, whereas s.c. inoculation induced uniformly generalized leukemia. Because of the behavioral differences between the s.c. and intradermal tumors, it appeared of interest to examine their comparative morphology by light and electron microscopy. Both s.c. and actively growing intradermal tumors are made up of identical nonphagocytic histiocytes and contain virus particles. They differ in the number of proliferating cells, which is larger in the s.c. tumors. Cell necrosis is a conspicuous feature of the regressing intradermal tumors and is manifested by large numbers of macrophages with engulfed lysed cells or cell fragments. The virus particles disappear before the tumors regress.