PROC and autoimmune polyendocrinopathy: Furthermore, in the 45 subjects who were aPL positive (32 APS and 13 SLE/aPL+), antithrombin titers were not correlated with titers of aCL (r = 0.018, P = 0.92), anti-β2GPI (r = 0.15, P = 0.31), or anti–activated protein C (r = 0.27, P = 0.31).