DESMIN EXPRESSION IN RHABDOMYOSARCOMA - INFLUENCE OF THE DESMIN CLONEAND IMMUNOHISTOCHEMICAL METHOD

Aim-To determine which, if any, of five commercially available desmin clones is most reliable at labelling desmin filaments and whether the enhanced polymer one step (EPOS) method of labelling is of any advanta ge in the routine diagnostic laboratory. Methods-Thirty four rhabdomyo sarcomas from the files at The Hospital for Sick Children, Great Ormon d Street, London, were studied. Four different desmin clones, DE-R-11, D33, DE-U-10, and PDE, were applied to each using the conventional ex travidin biotin peroxidase method. The D33 clone was also applied usin g the EPOS method. Results-The EPOS method incorporating D33 persisten tly scored more cells as desmin positive and was positive in four case s which were negative on staining with the other clones. Conclusions-T he D33 desmin clone used with the EPOS method is more reliable for ide ntifying desmin filaments in tumours than other desmin antibodies test ed. Different desmin clones using a routine technique label different rhabdomyosarcoma cells and therefore it is justifiable to use more tha n one clone.