Experiences with leukocyte adherence inhibition in human cancer.

The original hemocytometer leukocyte adherence inhibi tion technique has been used to study immunological reactivity of patients with a variety of tumors. Cellular activity was closely correlated with exposure to tumor of the appropriate type. Specificity and sensitivity in terms of having few false positives and false negatives were of the order of 90% or greater, and repeated testing of the same patients showed a high degree of reproducibility. Patients with tumors showed specific leukocyte reactivity at all stages of tumor growth, and there was no “eclipse' †̃ phase even in very advanced disease. In contrast to some other reports, there was no quantita tive relationship between initial adherence and degree of tumor spread; similarly, the degree of adherence inhibition with specific tumor extract does not systematically vary with extent of disease in tumor-bearing patients. Leukocyte reactivity persisted after tumor removal; in some cases where there was no clinical evidence of residual disease, the activity persisted for up to four years. In other cases, reactivity was lost after only a few months. Specific serum blocking factors were found in almost all patients with progressing tumors and only rarely in normal subjects. Their presence was detected at all stages of tumor growth, when the patient's ieukocytes are also demonstrably active. Blocking factors disappeared in patients' sera four to six weeks after successful tumor removal, and their reap pearance was a guide to tumor recurrence. The phenom enon of unblocking is also demonstrable by ieukocyte adherence inhibition.