Detection of interleukin-2 receptors on tumor cells in formalin-fixed, paraffin-embedded tissues

Purpose: Interleukin-2 receptors (IL-2Rs) are common targets for current immunotherapy protocols, which usually require demonstration of IL-2R expression on the tissue samples for patient eligibility. Currently there is no method to demonstrate IL-2R expression on formalin-fixed, paraffin-embedded tissues, which may be the only material available without further invasive surgery. Method: We applied the newly developed biotinylated tyramine enhancement step to our immunohistochemical method for detection of IL-2Rs. Formalin-fixed, paraffin-embedded tumor tissues from patients with Hodgkin's disease and several non-Hodgkin's lymphomas were used. Results: The new immunohistochemical method successfully demonstrated IL-2R expression on Reed-Sternberg cells from 9 of 37 patients with Hodgkin's disease and also on tumor cells from 9 of 9 patients with CD30+ anaplastic large cell lymphomas, 1 patient with adult T-cell leukemia/lymphoma, and 1 patient with lymphomatoid papulosis. Conclusions: IL-2R expression can be demonstrated on tissue samples that are formalin-fixed and paraffin-embedded. Detection of IL-2R is more sensitive in frozen tissues but may be overestimated in Hodgkin's disease because of high background staining of eosinophils and neutrophils. Antibody stain ing of IL-2Rs can be more specifically localized to the Reed-Sternberg cells in paraffin-embedded tissues, which are superior for screening Hodgkin's disease for expression of IL-2Rs in immunotherapy protocols. Tumor cells in virtually all cases of CD30+ anaplastic large cell lymphoma express high levels of IL-2R. This new method will be very useful for evaluation of patients for admission to immunotherapy protocols utilizing IL-2R antibodies and/or immunotoxins.