Tumour metastasis in mice with reduced immune reactivity. II. Studies with a highly antigenic MCA‐induced sarcoma in thymectomized and/or sub‐lethally irradiated C57BL/6J mice

Abstract

Spontaneous metastasis formation was studied in thymectornized andlor sublethally irradiated syngeneic C57BL/6/ mice of a highly antigenic MCA-induced The possible influence of immune reactions on spontaneous metastasis formation of two MCAinduced sarcomas was previously tested in bonemarrow-substituted radiation and thymectomized radiation chimeras of C57BL/6J mice (Boeryd and Suurkula, 1973). No effect on the spread of the sarcomas was noted. This suggested that the influence of immune reactions on the spread of the two sarcomas was negligible, or that the activity of the presumed counteracting immunological mechanisms (Klein, 1972) was equally depressed.The aim of the present work was to test these possibilities further by studying the effect of less extensive and varying degrees of immunosuppression on the spread of one of the previously used sarcomas. The experimental model was the same except that sub-lethal, instead of lethal, irradiation was used. This treatment depresses the humoral antibody response to sheep red blood cells (SRBC) and the homograft reaction in various strains of mice (Koller and Doak, 1960;Micklem and Brown, 1961; Rosenthal, 1969) and recovery is dependent upon the pre-

Tumour metastasis in mice with reduced immune reactivity. III. Studies with three weakly antigenic tumours in thymectomized and/or sub‐lethally irradiated mice

“…The Fisher permutation test for independent two-sample cases with significant limits given by Edgeworth's series (OdCn and Wedel, 1973) was used for evaluation of differences in humoral antibody response, skin graft survival, tumour weights and incidence of metastases. The pooling test technique for obtaining summarizing conclusions concerning the effects of the treatments was the same as previously used (Suurkiila and Boeryd, 1974).…”

“…The humoral antibody response against sheep red blood cells (SRBC) as well as the survival of allogeneic A/Sn skin grafts was determined as previously (Suurkiila and Boeryd, 1974).…”

“…MCG12 and EpCal were transplanted subcutaneously in the tail as previously (Suurkiila and Boeryd, 1974). MaCal was transplanted subcutaneously in the right flank since it did not grow well when transplanted in the tail.…”

“…The tumours were then excised and weighed. The animals were autopsied and the lungs prepared for microscopical investigation as previously (Suurkula and Boeryd, 1974). A few mice were discarded for the same reasons as in the previous work (Suurkiila and Boeryd, 1974).…”

“…With limited immunosuppression, i .e. thymectorny in combination with sub-lethal irradiation, it was however possible to enhance metastasis formation (Suurkiila and Boeryd, 1974). The fact that the immunosuppressive treatment could facilitate the spread of a highly antigenic sarcoma raised the important question whether the spread of lesser antigenic turnours would be similarly influenced.…”