Studies on the Kinetics of Transplantation Immunity1

Using the parameter of the number of tumor cells necessary to produce s.c. tumors in allogeneic animals at varying intervals after antigenic stimulation, immunity was found to be in force as early as 2 days after primary antigenic stimulation. It reached a peak at 8-10 days and had largely subsided by the end of a month. This method was also applied to the quantitative study of the onset, degree, and duration of immunity elicited by skin grafts. The results obtained with inocula of large numbers of tumor cells (IO7)were comparable to those obtained with massive skin grafts. The differences in the degree of antigenic stimulation resulting from different routes of inoculation were studied. It was found that the intradermal (i.d.) route of inoculation resulted in a more intense antigenic stimulation than the s.c. route. When both routes of inoculation were used simultaneously the pattern of growth of the s.c. tumor was influenced by the i.d. inoculation: an i.d. inoculum given 24 or 48 hr earlier caused marked sup pression of growth of the s.c. tumor, while when an i.d. inocula tion was preceded by an s.c. inoculation, although there was an appreciable effect on the growth size, the growth curves of the 2 tumors were always parallel. There was no correlation between cytotoxic activity and the degree of immunity in force at a given time.