T–T cell collaboration in rejection of a syngeneic SV40-induced sarcoma in mice

Abstract

SYNERGISTIC or collaborative interactions between sub-populations of thymus-dependent lymphocytes were first demonstrated against alloantigens in vivo in graft-versus-host reactions¹, and subsequently in vitro in mixed lymphocyte culture responses² and in generation of cytotoxic lymphocytes³. At least two distinct subpopulations of T cells are involved in the interactions leading to collaborative responses, one acting as an amplifier or helper cell and the other type functioning as the precursor of the effector cell. The interactions between these two T-cell subpopulations yield effects greater than would be expected when each population is examined alone. It is now known that many tumours possess specific antigens which are recognised in vivo and in vitro by syngeneic hosts. There has been extensive study on immune response to SV40-induced syngeneic transplantable mKSA cells of BALB/c mice in our laboratory^4–6. This tumour has been shown to possess tumour-associated antigens which can immunise specifically against the growth of mKSA cells. A very useful in vivo assay, the tumour cell neutralisation test (Winn assay), has been used successfully in our laboratory to measure the immune response to SV40 tumour associated antigens and to monitor the activity of various fractions during biochemical antigen purification^7–9. The rejection of the tumour was shown to be dependent on the presence of T cells⁸, however, it has not been established whether different subpopulations of T cells might be involved. There have been no reports on T–T cell collaboration in vivo or in vitro in immune responses to syngeneic tumours. The SV40 tumour system enabled us to investigate this important issue using the in vivo tumour cell neutralisation. Here we describe collaboration between subpopulations of T cells in the rejection of syngeneic SV40-induced tumour in mice.