Impaired production of interleukin-2(IL2) in patients with Graves' disease by newly developed IL2 radioimmunoassay.

We have developed a sensitive, reproducible and specific radioimmunoassay for human interleukin-2. Using 125I-labeled interleukin-2 and polyclonal rabbit antisera raised against recombinant human interleukin-2, a competitive inhibition assay was described which could detect 1 U/ml of human interleukin-2. Substances such as interleukin-1 alpha, interferon beta, nerve growth factor, tissue necrotizing factor, various hormones, peptides and lectins did not affect the assay. Interleukin-2 was measured in supernatants of culture media of stimulated human blood mononuclear cells. Kinetics of interleukin-2 production in seven normal lymphocytes revealed that in both PHA- and Con A-stimulations, the peak levels of interleukin-2 were seen at the end of 72 hours (113.9 +/- 54.4 U/ml, 111.6 +/- 37.3 U/ml, respectively) and then declined. Interleukin-2 levels in PHA- and Con A-stimulations of untreated Graves' disease were significantly lower (14.5 +/- 15.5 U/ml, 12.3 +/- 12.7 U/ml, respectively) than normal controls. However, the improvement of decreased interleukin-2 production in methimazole-treated patients with Graves' disease was observed (38.2 +/- 28.1 U/ml, 48.0 +/- 35.6 U/ml, respectively). The present study demonstrates the usefulness of quantitating human interleukin-2 produced by human blood mononuclear cells and that there exists an impaired production of interleukin-2 in Graves' disease.