Some approaches to improve the therapeutic effectiveness of adoptive chemoimmunotherapy with spleen cells from melphalan-treated BALB/c mice bearing a large MOPC-315 tumor.
Spleen cells from BALB/c mice that are in the process of eradicating a large MOPC-315 tumor following low-dose L-PAM therapy (L-PAM TuB spleen cells) were previously shown to be capable of bringing about the complete regression of a large (15 to 20 mm) s.c. MOPC-315 tumor in a substantial percentage of T-cell-deficient (athymic nude) mice that had been treated with low-dose L-PAM (adoptive chemo-immunotherapy; ACIT). Here we show that aggressive depletion of CD4+T-cells by treatment both of spleen-cell donors and of recipients with anti-L3T4 monoclonal antibody (MAb) greatly improved the therapeutic effectiveness of L-PAM TuB spleen cells in ACIT. In the light of the apparent importance of cytotoxic T-lymphocytes (CTLs) for tumor eradication in low-dose L-PAM-treated MOPC-315-tumor bearers, it is interesting that treatment of L-PAM TuB spleen-cell donors with anti-L3T4 MAb was found to result in the generation of enhanced splenic anti-MOPC-315 cytotoxicity. Although most athymic nude mice in which the tumor had apparently completely regressed following ACIT remained tumor-free, approximately 1/3 of the mice relapsed. However, a substantial percentage of the relapsing mice were rescued by a low dose of L-PAM, which was not effective in causing tumor regression in athymic nude mice bearing a comparably large tumor if the mice had not been subjected previously to ACIT. Almost all athymic nude mice that had been "cured" of a large MOPC-315 tumor by ACIT but did not resist a subsequent MOPC-315 tumor challenge were rescued by low dose L-PAM. Thus, the therapeutic effectiveness of L-PAM TuB spleen cells in ACIT may be improved by aggressive depletion of CD4+ T-cells, suggesting that a low dose of L-PAM, which leads to the acquisition of potent splenic-tumor-eradicating immunity in BALB/c mice bearing a large MOPC-315 tumor, does not eliminate completely (or possibly not at all) the inhibitory activity of CD4+ T-cells. In addition, athymic nude mice that are not endowed with fully protective tumor-eradicating immunity following ACIT still have a substantial residual anti-tumor immune potential that can be exploited to bring about eradication of a large tumor burden following low-dose L-PAM therapy.
Weiskirch
L M
LM
Department of Microbiology and Immunology, University of Illinois, Chicago 60680.
Mokyr
M B
MB
D000818:Animals; D004354:Drug Screening Assays, Antitumor; D005260:Female; D016219:Immunotherapy, Adoptive / Q000379:methods*; D008558:Melphalan / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009364:Neoplasm Recurrence, Local / Q000628:therapy; D009368:Neoplasm Transplantation; D010954:Plasmacytoma / Q000276:immunology / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors
D008558:Melphalan