Tube leukocyte adherence inhibition (LAI) assay in gastrointestinal (GIT) cancer

Tumor-specific immunity to carcinoma of the colon, pancreas and stomach was assayed by tube LAI. Cancers of the colon, pancreas and stomach, were shown to possess organ-type specific neoantigens. In 115 patients with colon cancer, 100%, 75%, 61% with Dukes' A, B and C cancer were LAI positive, respectively. Even a microfocus of in situ cancer in a colon adenoma was sufficient to stimulate measurable tumor-specific immunity in the host. In Dukes' D cancer, 25% of patients with widespread metastasis were positive, whereas 100% with solitary lesions were positive. Reactive leukocytes from patients with colon cancer did not react to extracts of normal bowel mucosa or villous adenoma from LAI-negative patients. Leukocytes from 19% (3 of 16) of patients with colon adenomas reacted to the extract of colon cancer but not normal colon mucosa. Moreover, the LAI-positive response of the patients with colon adenomas or colon cancer is directed to a colon cancer TSA which is linked to beta2-microglobulin. These studies suggest that some colon adenomas express TSA before morphological evidence of cancer. It is not known if the acquisition of a cell surface TSA is an irreversible step toward unrestrained growth and metastasis. In pancreatic cancer, 100% of patients with cancers less than 5 cm and without metastasis were LAI positive, whereas 29% were positive when the cancer was greater than 5 cm or had metastasized. In Patients with stomach cancer, 100% with Stage II and 46% with Stage III and IV cancer were LAI-positive. Leukocytes from patients with other GIT cancers and from patients with inflammatory bowel disease or pancreatitis did not react with extracts of colon, stomach or pancreatic cancer. Leukocytes from patients with metastatic cancer, usually did not react in the tube LAI assay because their surfaces were coated in vivo with TSA. LAI reactivity was present when CEA was not detectable and when CEA levels were elevated LAI activity was often absent. The present study suggests that the automated tube LAI shows sufficient promise to warrant studies to determine its efficacy for the diagnosis of GIT cancers.