Anti-phosphotyrosine and anti-phosphoserine antibodies in SLE sera

By using an ELISA method, we identified antiPTyr and antiPSer antibodies in the sera of some SLE patients. Afterwards, antiPTyr and antiPSer antibodies were purified by affinity chromatography on phosphotyramine-CNBr-Sepharose column and on phosphoethanolamine-CNBr-Sepharose, respectively, and the specificity of the purified antibodies was demonstrated by inhibition assays. The study pointed out a higher incidence of antiPTyr than anti PSer antibodies in the sera of these patients, which suggests that some "autoantigens" from membrane might be involved.