L2C guinea pig leukemia. A potential model for structuring multimodality therapy.

L2C guinea pig leukemia is a lymphoblastic neoplasm that arose spontaneously in a nonirradiated female strain 2 guinea pig over 20 years ago. Mutation of the original tumor probably accounts for the discordant results which have been reported. The LE-L2C subline was used to develop a multimodality therapy model of acute leukemia. Syngeneic strain 2 animals challenged with 3 x 10(5) LE-L2C cells developed overt leukemia in 14 +/- 3 (SD) days. When treated with cytoreductive chemotherapy, they relapsed with either systemic or central nervous system (CNS) disease. However, CNS relapse was prevented by craniospinal irradiation, yielding a uniform pattern of relapse. Preliminary studies suggest that active immunotherapy with nonspecific agents, such as BCG, or immunoreconstitution with thymosin may prolong the duration of remission and increase the percentage of long-term survivors. L2C leukemia may represent a useful animal model for structuring the principles that govern the interrelationship between chemotherapy and immunomudulation.