Immunohistochemical analysis of Hodgkin's disease using microwave heating.

AIMS To assess the effect of microwave heating on immunohistochemical staining of CD15 and CD30 antigens in Hodgkin's disease tissue samples. METHODS Formalin fixed, paraffin wax embedded sections from 20 cases of Hodgkin's disease (six mixed cellularity, 14 nodular sclerosis) were immunostained for CD15, using two antibodies (DAKO-M1 and Leu-M1) and for CD30 using the antibody Ber-H2. The staining was carried out by conventional techniques which included pretreatment of sections with trypsin and on untreated sections following heating with microwaves. With antibody Leu-M1 an additional method, using a specific antimouse IgM bridge both with and without microwave heating, was also included. The results for each method were compared by counting positively stained Reed-Sternberg cells and estimating the staining intensity. RESULTS Microwave heating resulted in a substantial increase in the number of cells stained with antibodies to CD15 and also in the staining intensity. The best results were obtained using Leu-M1 with specific rabbit anti-mouse IgM bridge and microwave heating. Dramatic enhancement of the staining of Reed-Sternberg cells for CD30 was achieved following microwave heating, together with disappearance of the non-specific staining of plasma cells. CONCLUSION Microwave heating is strongly recommended for the immunohistochemical staining of CD15 and CD30 expressed by Reed-Sternberg cells in Hodgkin's disease.