Radioimmunoassay of leukocyte (alpha) interferon and its application to some clinical conditions.

A radioimmunoassay for human leukocyte interferon alpha (alpha IFN) has been developed, using tracer produced by recombinant DNA (IFLrA) and polyclonal rabbit antiserum against partially purified leukocyte IFN (PP alpha IFN). Sensitivity was 4 units/ml using sequential saturation. Only lymphoblastoid IFN showed complete cross reactivity. Serum alpha IFN concentrations were measured in normal subjects and in patients with acute viral infections, bone and joint diseases, and malignancies. Some cases in the first two groups of patients had significantly elevated serum levels compared with controls. The pharmacokinetics of alpha IFN were studied in treated cancerous patients. Radioimmunoassay and biological assay gave similar and closely correlated results. Radioimmunoassay is thus a useful method for the routine assay of alpha IFN, especially in biological fluids containing low concentrations.