The Scl-70 antibody test is a blood test used to diagnose systemic sclerosis (SSc), also known as scleroderma. Scl-70 antibodies are proteins produced by the immune system that target a specific protein in the body. The test is performed by taking a blood sample from the patient and analyzing it for the presence of Scl-70 antibodies. A positive result may indicate the presence of SSc, but additional tests and clinical evaluation are necessary for a definitive diagnosis.