Anti-SM and anti-U1-RNP lupus antibody fine specificities.

Evidence for the presence of multiple shared epitopes on the target cellular antigens was found when 290 anti-Sm and anti-U1-RNP lupus sera were analyzed by immunoblotting. Forty-eight different immunoblot patterns were observed with the sera. Studies with selected antigen-affinity-purified antibodies confirmed the presence of multiple shared epitopes, in agreement with findings obtained with monoclonal antibodies. The results have implications for the design of effective diagnostics and for the use of these antibodies as molecular probes.