Lysozyme and albumin radioimmunoassays. New techniques for the study of proteinuria

To facilitate the study of mechanisms and patterns of proteinuria, radioimmunoassays for human lysozyme (LZM) and albumin (alb) were established to permit quantitation of physiologic amounts of these proteins in urine. Commercially available LZM and alb preparations were radiolabeled with I125, and single antibody, competitive protein binding assays were developed. Separation of free and antibody-bound radioprotein was achieved with 20 per cent polyethylene glycol. LZM and alb 24-hr excretion rates for 12 normal subjects were 7 to 64 microgram and 2.3 to 16.1 mg, respectively. Of 6 renal disease patients with undetectable urine LZM by bioassay, 5 were shown to have elevated LZM concentrations by radioimmunoassay. The ease of establishing and performing these assays and their reproducibility suggest that they may have clinical and investigative value.