These antibodies may also be found in patients with systemic lupus and occasionally in other autoimmune diseases, such as myositis. The finding of SS-A and/or SS-B antibodies is not specific to Sjögren’s syndrome patients. Accordingly, 20-40% of Sjögren’s syndrome patients may lack SS-A and/or SS-B antibodies.
However, it is very uncommon for SS-B antibodies to occur alone. SS-A antibodies thus occur commonly by themselves. SS-B antibodies are less common, being found in approximately 30-50% of Sjögren’s syndrome patients. SS-A antibodies are found in approximately 60-80% of Sjögren’s syndrome patients. SS-A and SS-B antibodies are examples of two antibodies that bind molecular targets within our own cells. If this mechanism goes awry, then we may form antibodies to self-material and be susceptible to autoimmune disease. Cells that produce antibodies against molecular targets on our own tissues are actively eliminated from our bodies, particularly early in life. Binding of such molecular targets is an essential step in our defense against infections and cancer. However, the large array of such antibody proteins in our blood ensures that a diverse and large number of molecular targets can be recognized. Each antibody protein has a binding site that can attach to only a very specific molecular target. These targets, termed antigens, are located on the surfaces of microorganisms, cells, and blood proteins. SS-A (Ro) and SS-B (La) antibodies: Antibodies are a large family of proteins in the blood that are capable of binding to molecular targets.The following tests are routinely performed in the evaluation of a patient with suspected Sjogren’s syndrome: