Physical Association of Two Nuclear Antigens and Mutual Occurrence of Their Antibodies: The Relationship of the Sm and Rnaprotein (MO) Systems in Sle Sera

Abstract An unexpected immunologic relationship was encountered when sera from patients with systemic lupus erythematosus directed against two different nuclear antigens in calf thymus extract were found to give a reaction of partial identity when reacted with a mixture of the antigens in agar diffusion experiments. Analysis of this antigenic mixture by absorption of the antigenic activity by monospecific antisera to such antigens has led to the conclusion that these two nuclear antigens designated Sm and Mo exist in calf thymus extract as a molecular complex. In addition to this physical association, human systemic lupus erythematosus sera containing anti-Sm were found to have an inordinately high concurrence of anti-Mo (17 of 19 sera).