The main objectives of this contract are for the contractor to perform enzyme linked immunosorbent assays (ELISA's) for soluble interleukin-2 receptors, for the contractor to assay human and cynomologus monkey antibodies directed toward both infused murine and humanized monoclonal antibodies, for the contractor to determine serum concentration of infused murine and humanized antibodies, and for the contractor to perform passive hemagglutination assays and ELISA's for serum antibodies to protein and polysaccharide antigens. These assays are integral parts of major ongoing clinical trials of the intramural research program, and are mandated by the Bureau of Biologics for ongoing intramural clinical trials. The assays represent repetitive procedures that are part of this integrated continuing program of the Metabolism Branch, NCI. Data obtained under this contract must be consistent with previous data, and delivered in a timely manner to the Project Officer and Metabolism Branch Staff, since results will be used for clinical care decisions made in real time.