Immune surveillance: Both CD3 super(+) CD4 super(+) and CD3 super(+) CD8 super(+) 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. Since most "NK-like activity" in freshly isolated populations appears to be associated with CD3 super(-) cells, whereas antigen-specific, MHC-restricted T cells mostly expressed CD3 determinants, CD3 was a good marker for evaluating the role of T cells and "NK" cells in tumor resistance in vivo. The approach used has revealed the important role of CD4 super(+) 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.