f32-Microglobulin Determined by Radioimmunoassay with Monoclonal Antibody

(/32-M) involving a commercially available monoclonal antibody, we used a second monoclonal antibody, produced in our laboratory, for affinity-chromatographic purification of /32-M. Both monoclonal antibodies bound to all of the charge isomers of f32-M identified by two-dimensional gel electrophoresis. Polyethylene glycol was used to separate the phases after incubation for 3 h at room temperature. Sensitivity was 0.25 ng of f32-M. Within-assay CVs were <5.4%, between-assay CVs <7.3%. Analytical recovery was 95-102%. The reference interval was 1.2-2.2 mg/L for 49 healthy subjects. The correlation coefficient for comparison with a polyclonal antibody assay was 0.99 7 for 44 patients. In a study correlating serum f32-M and creatinine concentrations with glomerular filtration rate for 50 patients, correlation coefficients for log-log transformed data were -0.94 and -0.95, respectively. Concentrations of f32-M were increased in serum of patients with impaired renal function and also in patients with normal renal function who had disorders involving the immunologic response. We found no clear-cut advantage of measuring serum f32-M over serum creatinine in the estimation of glomerular filtration rate.