RO60 and systemic lupus erythematosus: Double immunodiffusion studies showed that 63 SLE subjects (55.26%) did not have autoantibodies against extractable nuclear antigen (anti-ENA), 14 (12.2%) had antibodies against ribonucleoprotein (anti-RNP), 23 (20.18%) had anti-Ro60, 6 (5.26%) had anti-SmRNP, four (3.5%) had unidentified precipitin lines, and four (3.5%) had miscellaneous antibodies.