RADIOIMMUNOASSAY FOR SERUM APOLIPOPROTEIN-D, AN ATYPICAL APOLIPOPROTEIN - VALIDATION AND CLINICAL-APPLICATION

Apolipoprotein D (apoD) is an atypical apolipoprotein in terms of its structure, synthesis and probable function. It is the most abundant pr otein in breast cyst fluids of patients suffering from macrocystic dis ease of the breast, a disease associated with an increased risk of dev eloping breast cancer. We have developed and optimized a competitive r adioimmunoassay for the measurement of apoD in human serum. The assay uses a solid phase separation method and with a 4h incubation period, it can be completed in a single working day. The within and between ru n coefficients of variation were <8.5% and <12.2%, respectively, and q uantitative recovery of apoD was obtained over the range 250-5000 mu g /L. There was no difference in the serum concentrations of apoD betwee n female controls, patients with benign breast disease and early breas t cancer. However, serum apoD was significantly lower in breast cancer patients with bone metastasis.