The presence of human anti-mouse antibody (HAMA) has been associated with injections of murine monoclonal antibody for diagnostic and/or therapeutic purposes. Circulating levels of HAMA can bind to the injected IgG and reduce the efficacy of the antibody therapy. HAMA also can cause anaphylactic complications to subsequent administration of murine monoclonal IgG. Several studies have shown a correlation between HAMA status and clinical outcomes and prognosis. HAMA reactivity has been reported to occur in some individuals without known exposure to murine IgG. Such responses may be due to polyclonal rheumatoid factors, heterophilic antibodies, dietary, or other exposure. HAMA has been shown to interfere with many two-site immunoassay tests utilizing murine monoclonal antibodies, resulting in both false positive or false-negative results.

The presence of Rheumatoid Factor (RF) and/or heterophilic antibodies in the sample may interfere with the assay and could result in false-positive values. Lipemic serum samples may interfere with the assay and could result in false-positive values.