Pristane induces high titers of anti-Su and [formula omitted] autoantibodies in [formula omitted] mice Quantitation by antigen capture ELISAs based on monospecific human autoimmune sera

Abstract

Autoantibodies to Su and anti-nRNP Sm are common in human and murine systemic lupus erythematosus (SLE), and are also produced by BALB c mice with SLE-like autoimmunity induced by pristane. Antigen capture ELISAs employing monospecific human autoimmune IgG were developed to quantitate the production of anti-Su and anti-nRNP Sm autoantibodies in 77 sera from BALB c mice with pristance-induced autoimmunity. The sensitivity and specificity of the anti-Su antigen capture ELISA were 100% compared with immunoprecipitation of 35S-labeled cellular proteins. All 16 immunoprecipitation positive sera were positive in the anti-nRNP Sm antigen capture ELISA (100% sensitivity), whereas 55 61 immunoprecipitation negative sera were negative by ELISA (90% specificity). The 6 61 immunoprecipitation negative sera that were ELISA positive were probably true positives because subsequent sera obtained from the same mice were positive by both techniques. Thus, the antigen capture ELISA may be somewhat more sensitive than immunoprecipitation. The titers of anti-Su and anti-nRNP Sm positive antibodies in the sera were as high as 1:25 000–1:250 000 by ELISA, suggesting that autoantibodies may be produced in pristane-primed BALB c mice at levels comparable to those seen in spontaneous autoimmune disease. We conclude that antigen capture ELISAs based on human autoimmune sera were highly sensitive and specific for detecting murine anti-Su and anti-nRNP Sm antibodies. This technique will be useful for quantitating antibodies in murine autoimmune disease models, since antigen capture ELISA avoids the use of denatured or recombinant antigens, permitting antibodies recognizing tertiary and quaternary structures to be detected.