We are familiar with the antibodies SS-A(Ro) and SS-B(La). Is there any more information on the origin of the names Ro and La.

Response from

from Mark Genovese, MD, 11/07/00
The origin of these names dates back several decades. The term Ro was first used in reference to the serum of a single patient (Ro), from which antibodies could be found reacting to a soluable cytoplasmic antigen.[1] This patient had a syndrome resembling systemic lupus erythematosus (SLE) but did not have serum that demonstrated reactions to nuclear components. The term La was similarly first coined in reference to a soluble cytoplasmic RNA protein antigen to which antibodies were found in the sera of patients with SLE and also in a small group of patients who appeared to lack antinuclear factors (as it was described at the time) but who had a clinical picture consistent with SLE.[2] The antigen was first identified in calf thymus extract and reacted to the serum of a single patient (La).[2] Work going on during the same era in other laboratories led to the identification of antibodies against similar antigens, and these were independently termed anti-SS-A and anti-SS-B. For a better understanding of the development of the field, antigens, and antibodies, see an excellent review by Pisetsky.[3]


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