Simultaneous analysis of microheterogeneity of immunoglobulins and serum protein fraction using high‐voltage isoelectric focusing on six cellulose acetate membranes

A systematic detection method for the single performance of cellulose acetate (CA) membrane isoelectric focusing to detect six different types of information on protein abnormalities was developed. High-voltage isoelectric focusing was carried out on six layers of CA membrane using a thermoelectric cooling apparatus. After electrophoresis, the proteins on the top, the third, the fourth, the fifth, and the bottom CA membrane were transferred to a polyvinylidene difluoride (PVDF) membrane by a simple contact printing procedure to detect IgM, kappa-chain, lambda-chain, IgA, and IgG, respectively. Each PVDF membrane revealed the microheterogeneity of these immunoglobulins using specified anti-serum and enzyme immunostaining. The second CA membrane was stained with Coomassie brilliant blue G250 to detect serum protein patterns. All stained membranes showed clear electrophoretic patterns of immunoglobulin microheterogeneity. By our method, immunoglobulin abnormalities in serum could be screened out using six different types of information obtained simultaneously.