Detection of antigens on nitrocellulose paper immunoblots with monoclonal antibodies.

A very sensitive method for the detection of antigen-antibody complexes on nitrocellulose paper immunoblots is described. The protein antigens are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by their electrophoretic transfer onto a nitrocellulose sheet ("Western blot"). The protein antigens bound to the nitrocellulose paper are exposed to the monoclonal antibody and the antibody-antigen complexes are detected on the paper by an immunoenzymatic reaction. The improved sensitivity of this method is the result of (i) the use of the detergent Tween 20 in blocking the nonspecific binding of the antibodies to the nitrocellulose paper, (ii) the use of a peroxidase-antiperoxidase (PAP) reaction, and (iii) the intensification of the diaminobenzidine reaction product with nickel and cobalt ions in phosphate buffer.