Effector mechanisms in allograft rejection. III. Kinetics of killer cell activity inside the graft and in the immune system during primary and secondary allograft immune responses.

The cells recovered from sponge matrix allografts and from various lymphoid organs of recipient mice were tested for their ability to perform relevant target cell lysis in vitro. In the primary response, the peak cytotoxic activity was detected 8 days after transplantation, inside the graft, in regional lymph nodes, and in the spleen. In the secondary response, the peak cytotoxic activity in the regional lymph nodes and in the spleen took place promptly, 4 days after transplantation. The peak activity inside the graft was recorded on day 7. In the primary response, the activity inside the graft had declined. In the secondary response, the cytotoxic activity in the blood was low, and significant cytotoxic activity appeared only after the activity in the blood was high and demonstrated a biphasic profile, with one peak on day 3--4 and another activity peak on day 14. Killer cells were detected inside the graft for a far longer time in the primary (4 weeks) than in the secondary (2 weeks) response. I conclude that cellular kinetics in the secondary anti-allograft response is qualitatively but possibly not quantitatively different from the primary response.