Coupling of protein antigens to erythrocytes through disulfide bond formation: preparation of stable and sensitive target cells for immune hemolysis.

AUTOR(ES)
RESUMO

An efficient technique has been developed for coupling protein antigens to erythrocyte membranes. The procedure involves three steps. First, 3-(2-pyridyldithio)propionyl residues are introduced into the protein by reaction with a heterobifunctional reagent, N-succinimidyl 3-(pyridyldithio) propionate. Second, the addition of disulfide groups to sheep erythrocytes (SRBC) is achieved by coupling dithiodiglycolic acid to SRBC with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The disulfide bonds of the dithiodiglycolyl-SRBC conjugate are then reduced with dithiothreitol. Finally, the 3-(2-pyridyldithio)propionyl-protein conjugate is covalently coupled to the thiolated SRBC through thiol/disulfide exchange to form the disulfide-linked antigen-SRBC conjugate. The procedure requires only 10-500 microgram of protein antigen for the preparation of 50 microliter of packed protein-coupled SRBC. Antibodies binding to antigen on the erythrocyte initiate a complement-dependent immune lysis of the target cells. Target cells prepared by this method are stable for at least 4 wk at 4 degrees C in phosphate buffer (pH 7.2) and are capable of detecting as little as 40 pg of antibody in a hemolytic assay without noticeable nonspecific lysis.

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