Resting normal cells do not express interleukin-2 receptor (IL-2R). The receptor is expressed by some of the activated cells such as those in certain forms of lymphoid malignancies, autoimmune diseases, and graft rejection. Taking advantage of this property of IL-2R, several IL-2R directed clinical trials have been reported with variable successes. For example, IL-2 combined to diphtheria toxin induced significant tumor regression in patients with hematologic malignancies. In the past, investigators were, however, unable to demonstrate the relationship between the level of IL-2R expression and tumor response primarily because of the inability to accurately measure the high affinity IL-2R levels. Monoclonal anti-Tac conjugated with a pseudomonas endotoxin or fusion toxin consisting of IL-2 and PE40 also have been developed to target IL-2 expressing cells.In addition, the monoclonal antibodies prepared against IL-2 receptor induced remission in some patients with T-cell leukemia. These studies support the need for development of a rapid, sensitive, specific, and uncomplicated assay to measure IL-2R levels. Based on their experience with receptor transcript phenotyping (RTP) assay for erythropoietin receptor, the Investigators now propose to develop and assay based on PCR quantitation of IL-2R subunit messenger RNAs from peripheral blood mononuclear cells and sorted tumor biopsies. They will design and test PCR primers specific for IL-2Ra mRNA and determine the tissue specificity of the RTP assay by screening several cell lines. The quantitative aspect of the PCR will be tested first by normalizing dilutions of samples with internal standard such as GAPDH gene. The Investigators, however, will attempt to develop absolute quantitation of IL-2a mRNA by template competition. Finally, binding assays will be performed to determine by Scatchard analysis the affinity of binding sites on selected cell lines.
