Detection of circulating intercellular adhesion molecule‐1 antigen in malignant diseases
A new monoclonal antibody (MoAb) H A58 (IgG 1) was prepared, which recognizes the binding site on the intercellular adhesion molecule‐1 (ICAM‐1) antigen to the lymphocyte function‐associated antigen‐1 (LFA‐1). The double‐determinant immunoassay (DDIA) was established with use of MoAb HAS8 and another anti‐ICAM‐1, MoAb CL207, to detect the soluble, shedding ICAM‐1 antigen. Human recombinanl interferon‐gamma (IFN‐γ) induced not only the expression of cell surface ICAM‐1, but also the shedding ICAM‐I antigen in an IFN‐y concentration‐dependent and incubation‐time‐dependent manner. DDIA was applied to detect the shedding ICAM‐1 antigen in the sera of patients with malignant or benign diseases. The incidence of posilivity for ICAM‐I antigen in malignant diseases was higher than that in benign diseases or in healthy controls. Furthermore, the sera of cancer patients with liver metastasis showed higher levels of the shedding ICAM‐1 antigen. These findings suggest that serum ICAM‐1 antigen may be a useful marker to monitor tumor burden in cancer patients.