HAMA INTERFERENCE WITH MURINE MONOCLONAL ANTIBODY-BASED IMMUNOASSAYS

The application of murine monoclonal antibodies (mMAbs) for radioimmun oscintigraphy and for disease therapy has resulted in a significant nu mber of patients with elevated blood levels of human antimurine antibo dy (HAMA). During the past few years, increasing numbers of laboratori es have reported that HAMA can cause false results when murine monoclo nal antibody-based in vitro tests are performed; HAMA has been demonst rated to produce both false-positive and false-negative results. Diffe rent approaches to solving this ''HAMA-interference problem'' have bee n proposed, and have been effective on a limited basis. However, the t ask of making mMAb-based in vitro assays ''HAMA-proof'' for use in cli nical laboratories presents a formidable challenge. This report review s the problem of HAMA interference with mMAb-based in vitro assays, an d presents data on the clinical sensitivity and specificity of ImmuSTR IP(R) HAMA IgG enzyme immunoassay (EIA), a research assay being used t o detect and quantitate HAMA in patients receiving injections of mMAbs . Additionally, elevated levels of preexistent HAMA have been detected with this assay in sera that test positive for rheumatoid factor; the significance of this observation is also addressed.