Adoptive T cell immunotherapy of MSV-induced tumours in nude mice. Part II. Sequential analysis of serum immune complexes and blocking activity in reconstituted mice in relation to tumour biology.

In seven separate experiments, nude (nu/nu) mice carrying established murine sarcoma virus (MSV) tumours were reconstituted with syngeneic (+/+) immune splenic T cells. These immune protected mice were randomly divided to provide smaller groups for serial exsanguination. At various time points mice were individually bled and CIC concentration and blocking activity of each individual serum was determined. Control sera were obtained from nu/nu and adult +/+ mice inoculated with tumour cells only, and from nu/nu mice protected with normal +/+ spleen cells. In all the mice studied, CIC and blocking appeared to be mutually independent parameters throughout the MSV tumour course. On the other hand, in immune protected mice considered alone or together with the control groups, CIC and time after tumour cell inoculation, but not tumour size, were significantly correlated. A significant relationship between blocking and tumour size was also established, although this only applied to immune protected mice. However, analysis of the combined data from sequentially bled immune protected mice in relation to different phases of tumour behaviour, did not support the notion that blocking, and more particularly the persistence of CIC, contribute to tumour regrowth and dissemination.