Cell-Mediated Immunity and Specific Serum Factors in Human Cancer: The Leukocyte Adherence Inhibition Test

Blood leukocytes from patients with cancer (malignant melanoma; adenocarcinoma of colon, rectum, and breast) reacted with aqueous extracts of tumors of the corresponding type, with the result that adherence of the leu kocytes to glass was diminished. Leukocytes from normal individuals did not react. The leukocyte adherence inhibition (LAI) test could be completed in a few hours. Sera from tumor-bearing patients blocked the LAI reaction of their own leukocytes or leukocytes from other patients with the same type of tumor. Serum blocking activity was lost soon after surgical removal of the tumor; the patient’s serum then became unblocking. The LAI technique gave consistent results in a series of patients, analogous to those reported with the lymphocyte cytotoxicity test, and was easier and quicker.