Immune surveillance: both CD3+ CD4+ and CD3+ CD8+ T cells control in vivo growth of P815 mastocytoma.
The aim of this study was to examine whether a spontaneous immune response controls neoplastic growth in P815-bearing DBA/2 mice, and to characterize the cells involved in tumor resistance in vivo. Several cell lineages such as T-cell-receptor (TcR)-bearing T cells, NK cells and macrophages mediate some anti-tumor activity in vitro. P815 was chosen as a model because it is weakly immunogenic and is a good target both for tumor-specific, MHC-restricted CTL-mediated lysis and for MHC-unrestricted lysis exerted by long-term cultured lymphocytes or activated macrophages. Since most "NK-like activity" in freshly isolated populations appears to be associated with CD3- cells, whereas antigen-specific, MHC-restricted T cells mostly express CD3 determinants, CD3 was a good marker for evaluating the role of T cells and "NK" cells in tumor resistance in vivo. The survival of anti-CD3-treated animals that were inoculated with tumor cells was strongly reduced (mean survival time: 17 days vs. 40 days for the control group) and was associated with increased tumor growth rate. We followed the same approach to define the T-cell subset(s) that mediate(s) this immune response. Both CD4+ and CD8+ T cells were required for induction of immune control on neoplastic growth. The approach used has revealed the important role of CD4+ T cells in immune responses that control in vivo growth of a class-I-positive, class-II-negative tumor and suggests that these cells may play a central role in tumor resistance. Since CD4+ cells are activated by soluble, exogenous proteins, this finding may have important implications for immunotherapy.
Laboratoire de Physiologie Animale, Université Libre de Bruxelles, Rhode-St.-Genèse, Belgium.
V
V
Flamand
C
C
Biernaux
M
M
Van Mechelen
T
T
Sornasse
J
J
Urbain
O
O
Leo
M
M
Moser
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002455:Cell Division; D000939:Epitopes / Q000032:analysis; D007108:Immune Tolerance; D008748:Methylcholanthrene; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D012513:Sarcoma, Experimental / Q000276:immunology* / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008748:Methylcholanthrene