The present application provides compositions and methods useful for detecting and monitoring autoimmune diseases in a human subject. The methods comprise providing a moesin fragment for binding to an anti-moesin autoantibody and contacting the moesin fragment with a sample obtained from the human subject. The moesin fragment comprises the entire N-terminal FERM domain of a human moesin protein. The human subject has or is suspected of having an autoimmune disease such as connective tissue disease, systemic sclerosis, Sjogrens syndrome, or systemic lupus erythematosus.
