Studies of Immunity in Mice Surviving Systemic Leukemia L1210

Abstract

The current studies conducted in first generation (BALB/cAn × DBA/2J)F₁ hybrid male mice show that mice surviving systemic leukemia L1210 as the result of treatment with the halogenated derivatives of amethopterin, 3′,5′-dichloroamethopterin and 3′bromo-5′-chloroamethopterin, may become immune to reinoculation of the leukemia. This phenomenon could not be attributed to any persistence of the halogenated derivatives of amethopterin in the host. Many of the long-term survivors of systemic leukemia appeared markedly immune to reinoculation, the reinoculum showing no evidence of growth. Other surviving mice showed partial immunity, the reinoculum growing slowly and killing the mice considerably later than is ordinarily observed with this leukemia. For the partially immune mice a positive correlation was observed between the size of the local tumor prior to death and the time of death. Evidence was obtained that the slow growth of the tumor in a partially immune mouse did not persist on transfer. The immune state may persist and was demonstrable on repeated reinoculation of the leukemia. Such immune mice appeared to be free of leukemic cells. The appearance of immunity was less readily demonstrable on successful treatment initiated early, when the disease is relatively localized. Transfer of blood or spleen of DBA/2J mice to the hybrids failed to elicit an immune response against the leukemia. BALB/cAn mice were also found to be immune to leukemia L1210 after spontaneous regression of the tumor. Immunological phenomena in chemotherapy studies of the host-tumor relationship are discussed.