NEW MONOCLONAL-ANTIBODIES AGAINST THE PUTATIVE IMMUNOSUPPRESSIVE SITEOF RETROVIRAL P15E

Both retroviral infections as well as human tumors may cause immunosup pression. One of the factors involved in immunosuppression in patients with squamous cell carcinoma of the head and neck (SCC-HN) is a prote in related to the retroviral protein p15E. A conserved, 17-amino acid sequence represents the immunosuppressive epitope of retroviral p15E. In order to study the relationship between SCC-HN associated immunosup pression and retroviral p15E, we produced three new monoclonal antibod ies (MAbs; ER-IS1, ER-IS2, and ER-IS5) directed against the immunosupp ressive synthetic CKS-17 peptide. These MAbs react with the immunosupp ressive peptide (in enzyme-linked immunosorbent assay), with human tum or cell lines (in FACScan analysis), with retroviral p15E (on Western blot), and with cryostat sections of SCC-HN tumor tissue. In addition, the MAbs neutralize the immunosuppressive low molecular weight factor s present in sera of patients with SCC-HN. These results show that ret roviral p15E and the immunosuppressive factors associated with SCC-HN share a conserved immunosuppressive epitope and that MAbs against this epitope can be used for detection and neutralization of the tumor-ass ociated immunosuppressive protein(s).