DETECTION OF ANTI-PL-12 AUTOANTIBODIES BY ELISA USING A RECOMBINANT ANTIGEN - STUDY OF THE IMMUNOREACTIVE REGION

Autoantibodies to aminoacyl-tRNA synthetases are highly associated wit h myositis and detection is important in clinical diagnosis; however, current methods of screening limit its clinical utility. In the presen t study, alanyl-tRNA synthetase (PL-12) recombinant protein was obtain ed by immunological screening of a HeLa expression library and used in an ELISA with 22 anti-PL-12 sera, 200 autoimmune sera negative for PL -12 and 100 healthy individual sera. Sensitivity of the method was 95% (21/22) and specificity 100%. Mapping of the immunoreactive region wa s carried out using three anti-PL-12 sera and different recombinant pr otein-derived peptides. Results show that the same conformational epit ope located within amino acids 730-951 of the PL-12 antigen outside th e catalytic region was recognized by the three anti-PL-12 sera tested. We conclude that ELISA using recombinant protein is an effective and useful method for routine screening for anti-PL-12 autoantibodies.