[Human anti-murine immunoglobulin antibodies as disturbing factors in TSH determination].

Monoclonal murine antibodies are increasingly used for immunotherapy and in vivo diagnostic procedures such as immunoscintigraphy. The therapeutic or diagnostic reagent however, is a foreign antigen, which may induce host reactivity. This may interfere with the therapeutic or diagnostic reagent in vivo, resulting in a loss of efficacy or the necessity to increase dosages. In addition, there is an important interference to in vitro immunoassays detecting specific antigens utilizing murine monoclonal antibodies. In the present study, sera of patients who had undergone a therapeutic trial using 140 mg of an anti-CD4 antibody, were investigated. Human anti-murine-immunoglobulin-antibodies (HAMA) were detected 2-3 weeks after treatment was started and reached maximal amounts of 0.8 micrograms/ml after a single and 2 micrograms/ml after a repeated treatment course. Parallely raised values of TSH were found in sera containing HAMAs of more than 0.3 micrograms/ml. Elevations of TSH levels up to 13 microU/ml were most pronounced after a repeated trial of the murine antibody and were detectable up to 20 weeks.