MEASURES TO OVERCOME HAMA INTERFERENCES IN IMMUNOASSAYS

The incidence of human anti-mouse antibodies (HAMA) in different patie nt ser-a panels may be debatable the interference of HAMA, if present, in immunochemically based assays is, however, a fact This interferenc e can lend to falsely elevated or depressed results depending on the n ature of the HAMAs involved and the particular assay format chosen. Fo r several reasons, assays for serum tumor markers may be especially pr one to HAMA interference. Consequently, in the development of such ass ays, special attention should be given to the HAMA issue. In our exper ience, the degree of HAMA interference varies greatly from one assay t o another: Nevertheless, the HAMA issue has to be addressed. Several m ethods have been described to remove HAMA (and other interfering subst ances) via sample pretreatment. Alternatively, there are also some opt ions to counterbalance the potential effect of HAMA by using assay rea gents optimized for minimal HAMA susceptibility, e.g. inclusion of an excess of non-relevant mouse antibodies. However, there is no guarante e that any given assay will not be affected by HAMA. This is especiall y true if a portion of the HAMA in a patient's sample is comprised of anti-idiotypic ''internal image'' antibodies.