Value of HAMA--determination in clinical practice--an overview

HAMAs (human anti mouse antibodies) in serum of patients may be stimulated as an immunologic reaction to the application of animal protein. They are differentiated into heterophilic (species-unspecific) and mouse-specific anti-isotypic (often IgG1) or-idiotypic antibodies as well as according to the human immunoglobulin type (IgG or IgM). Besides infrequent clinically immunologic side effects (anaphylactic reaction), their influence on tumor marker measurements predominates in the follow-up of tumor patients by the possible impairment of newly applied monoclonal antibodies. The detection of HAMAs is performed on suspicion of a tumor by self-made or commercial tests, however, there is no consensus standardization of tests, standards and controls. Experiences are reported herein on the occurrence of heterophilic antibodies, reasons of suspicion, detection and removal, comparative determination of HAMAs by two commercially available tests (ImmunoSTRIP HAMA, Enzygnost) and HAMA induction in patients following immunoscintigraphy (OC-125, n = 27). Besides the rare appearance of HAMAs in patients without pretreatment or following biologic therapy, i.v. application of monoclonal antibodies for diagnosis (immunoscintigraphy) or therapy represents the most frequent reason for HAMA development that should always be ruled out in case of anamnestic indication and clinically unexplained tumor marker changes.