During the past 20 years, different biological activities have been described about lymphokine produced by activated leucocytes. Interleukin-1 is a factor produced by activated mononuclear phagocytes and is essential for supporting both T and B cell responses. On the other hand, activated T cells produce a factor called Interleukin-2 which is 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 Interleukin-2 and dysfunction of Interleukin-2 receptor have been found in several diseases, including autoimmunity, graft-vs-host rejection, acquired immune deficiency, lymphoadenopathy, and cancer. Thus a strong rationale exists for the investigation of determination of Interleukin-2 and Interleukin-2 receptor. Phase I of this study will: a. develop a sensitive ELISA assay for the measurement of IL-2 and IL-2R in the same sample of cultured lymphocytes; b. determine the optimal conditions for the assay; and c. determine the sensitivity of the assay by comparison with bioassay. Phase II of the study will involve the measurement of IL-2 and IL- 2R in normal subjects as well as patients with cancer, AIDS, arthritis, SLE, pemiphigus and transplantation subjects and others. When sufficient clinical data has been accumulated, the assay will be converted into a kit form for research and clinical use after submission to the FDA for approval. The PI has had extensive experience in working with lymphokines, particularly interleukins, and is confident that not only will the assay be developed without undue difficulty, but that the assay can be reduced to kit form to facilitate the diagnosis of immune dysfunction diseases.