CALR and systemic lupus erythematosus: Of the 34 patients with a single initial specificity, 10 (29%) had detectable antibodies against 60 kD Ro, 8 (24%) to nRNP A, 6 (17%) to phospholipids and 5 (15%) had rheumatoid factor (IgG and/or IgM) as the initial sole lupus autoantibody detected.