Inhibition of the growth of lymphoid tumours in syngeneic athymic (nude) mice.

A comparison of the growth of a number of BALB/c tumours in BALB/c, BALB/c.nu/ + (heterozygous nude) and BALB/c.nu (homozygous) nude mice has shown that a majority of BALB/c lymphoid tumours grow at a significantly reduced rate in BALB/c.nu mice. The three non-lymphoid BALB/c tumours (carcinomas and sarcomas) tested and a minority of lymphoid tumours, however, grew as well, or better, in the BALB/c.nu mice. Furthermore a correlation, without exception to date, has emerged from a comparison between the susceptibility of a tumour cell line to in vitro lysis by spleen cells from syngeneic nude mice and its growth in vivo in syngeneic nude mice. Only those lymphoid tumour cell lines lysed in vitro show the reduced growth rate in syngeneic nude as compared to syngeneic normal mice. Tumour cell lines, both lymphoid and non-lymphoid, which are resistant to in vitro lysis do not show the reduced in vivo growth rate in syngeneic nude mice. Both the in vivo and in vitro effect can be partially abolished by irradiating the nude mice prior to use, suggesting that a radiation-sensitive non-T-cell surveillance of lymphoid tumours is operating in nude mice. While the identity of the antigens is still unknown, the specificity of the phenomena suggest that C-type RNA oncogenic viral determined antigens are involved.