STUDIES ON CELL‐MEDIATED IMMUNITY IN PATIENTS WITH COLORECTAL CANCER: LEUCOCYTE MIGRATION INHIBITION TEST USING ALLOGENIC 3M KCI EXTRACT

Leucocytes from patients with colorectal and other malignant and non-malignant gastrointestinal diseases as well as those from normal subjects were tested by the leucocyte migration inhibition test (LMIT), employing the method of Clausen, using five different allogenic 3M KCI soluble extracts of colorectal cancer tissue. The normal range of migration index (Ml) was found to be > 0.82 and > 1.20 by calculating the mean Ml ± 2SD of ten normal subjects with cancer extracts. Mis out of this range were considered to be pathological. In LMIT with a single tumour extract, a pathological Ml was found in 46% of 50 colorectal cancer patients, a significantly higher figure than found in the three other groups of patients (4% to 16%). In the panel mode of LMIT, that is, testing each blood sample with five different tumour extracts, 40/50 (80%) of patients with colorectal cancer were reactive, while 2/15 (13%) of gastric cancer patients showed a “positive” reaction; no positive reactivity was observed in the other two groups of patients. Thus “positive” reactivity was significantly commoner in patients with colorectal cancer than in patients belonging to the other groups. The frequency of “positive” reactivity was higher in patients with Dukes C carcinoma than in those with Dukes A or B carcinomas, though differences were not significant. In the follow-up study, marked depression of reactivity was seen 10 to 14 days after curative resection. In patients without recurrence, leucocyte migration was found to be in the normal range during the two to four weeks after surgery. “Positive” reactivity reappeared in patients with local recurrence. Thus the LMIT, particularly when tested by a panel mode, by demonstrating cell-mediated immunity against tumour-associated antigens of colorectal cancer, provides a method of monitoring colorectal cancer activity.