Induction of Primary and Secondary Cell-mediated Cytotoxic Responses in Vivo

the Animal Production Branch, Division of Research Serv ices, NIH, Bethesda, Md. Growth of FBL-3Tumor Cells. The FBL-3 cells were a Friend virus-induced leukemia in B6 mice (10). Inoculation of as few as 1 x 10@cells i.p. produced progressive tumor growth and eventually killed the hosts (progressors). In contrast, s.c. inoculation of up to 5 to 15 x 106 cells pro duced only transient tumor growth, with subsequent corn plete regression (regressors). Growth of s.c. tumor was expressed as tumor volume and was calculated according to the method of Attia et a!. (1) as V = 0.4 x a x b where a