Nylon-wool-eluted lymphocytes, isolated from a site of
tumor rejection in Balb/c mice expressing concomitant
tumor immunity, were examined for their ability to inhibit the growth of the EMT6
tumor.
Tumor growth inhibition was monitored after co-inoculation of lymphocytes and
tumor cells into naive mice in a Winn-type adoptive-transfer assay. A pre-implanted
gelatin sponge was employed to capture the tumor-infiltrating lymphocytes. Mice harboring primary
tumors were implanted 8 days later with
gelatin sponges. The pre-implanted sponges were then inoculated with a secondary
tumor challenge 2 days after implantation of the sponge (i.e. 10 days after primary
tumor challenge). On day 17 (7 days after secondary
tumor challenge), the immune sponges were retrieved, digested in
collagenase and the T lymphocytes were isolated using a
nylon-wool column. Blank sponges (lacking
tumor cells), obtained from primary-
tumor-bearing or non-
tumor-bearing animals, were included for comparison. The data showed that T lymphocytes isolated from immune sponges inhibited
tumor growth while T lymphocytes recovered from blank sponges did not. At an effector:target (E:T) ratio of 10:1 the lymphocytes from the immune sponges were able to prevent totally the growth of
tumors in all cases (100% inhibition). This ability was reduced (60% inhibition) at an E:T ratio of 1:1. Comparison of the antitumor activities of the immune-sponge-derived cells with those from the spleen of the same animal revealed the superiority of the former. Depletion of immune-sponge-derived cells with anti-Thy1.2, anti-Lyt2.2 or anti-L3T4 and
complement resulted in a marked decrease in
tumor-inhibitory activity. These results indicate that T lymphocytes, expressing Thy1.2, Lyt2.2 or
L3T4 antigens, are involved in conferring protection to Balb/c mice against the EMT6
tumor.