Combined effects of chemotherapy and immunity against leukemia L1210 in DBA-2 mice.

SUMMARY DBA/2 mice inoculated with the strain-specific leukemia L1210 survived more than 50 days as a result of the combined effects of drug treatments and immunity. Differences in Li 210 immunogenicity were noted among 3 sublines of DBA/2 mouse strain. The therapeutic effects occurred also in DBA/2 sublines in which L1210 is weakly immunogenic and at drug doses which are immunodepressant per se. More than 60% of DBA/2 Ha-DD mice inoculated with leu kemia Li2iO survived longer than 50 days after combined treatments with 4,4'-diacetyl-diphenyl-urea-bis(guanylhydra zone)dimethanesulfonate and arabinosylcytosine. The cured mice were resistant to reimplantation of L1210. This resist ance was transferred to mice previously not exposed to the leukemia by the inoculation of immune serum, spleen or lymph node cells. The thereapeutic effects against L1210 were reduced in preirradiated hosts. DBA/2 Ha-DD mice were sensi tized against L1210 also by repeated immunization with X ray-killed leukemic cells. The incidence of chemotherapeutical ly induced cures was about 20 and 5% in DBA/2J and DBA/ 2Cr mice respectively. Also, in these sublines the cured mice were immune to Li210. Synergism between drugs and either passive or adoptive immunity were seen in both DBA/2Cr and DBA/2Ha-DD mice inoculated with serum or spleen cells from hyperimmune DBA/2Ha-DD mice. Accelerated rejection of DBA/2J skin occurred in DBA/2Ha DD mice immune to L1210. DBA/2Ha-DD mice could be sen sitized against L1210 by immunization with DBA/2J or DBA/ 2Cr skin grafts. The survival of reciprocal skin grafts between DBA/2J and DBA/2Ha-DD mice was prolonged by the 2 drugs at doses exerting therapeutic effects against Li210. The anti leukemic effects of the 2 drugs were reduced by pretreatments with the same drugs at therapeutic doses.