During the past 20 years, different biological activities have been described for lymphokines produced by activated leukocytes. Interleukin-1 (IL-1) is a factor produced by activated mononuclear phagocytes and is essential for supporting both T-cell and B-cell responses. Activated T cells produce interleukin-2 (IL-2), a factor necessary for T-cell proliferation. This soluble factor exerts its biological effects by interacting with specific high-affinity receptors on the surface of activated T cells. A decrease in the ability to produce IL-2 and dysfunction of interleukin-2 receptors (IL-2Rs) have been found in several diseases, including autoimmunity, graft versus host rejection, acquired immune deficiency, lymphoadenopathy, and cancer. Thus a strong rationale exists for the investigation of IL-2 and IL-2R.Phase I of this study will develop a sensitive ELISA assay for the measurement of IL-2 and IL-2R in the same sample of cultured lymphocytes; determine the optimal conditions for the assay; and determine the sensitivity of the assay by comparison with a bioassay. Phase II will involve the measurement of IL-2 and IL-2R in normal subjects and in patients with cancer, AIDS, arthritis, SLE, and pemphigus, as well as in transplantation subjects and others. When sufficient clinical data have been accumulated, the assay will be converted into kit form for research and clinical use.National Institute of Allergy and Infectious Diseases (NIAID)