APOH and autoimmune polyendocrinopathy: It was observed that in the absence of this serum co-factor, there was a reduction in cleaved caspase-3 in the presence of APS IgG (Figure 5a), but when human β2GPI was added back into the system to a final concentration typically observed in humans, levels of cleaved caspase-3 were enhanced back to levels similar to that seen previously.