 PAI-2 assists PAI-1 in regulating fibrinolysis and may help prevent overexpression of PAI-1, which increases risk of thrombosis.Over the course of a pregnancy, PAI-2 plasma concentration rises from nearly-undetectable levels to 250 ng/mL (mostly in glycosylated form).Among immune cells, macrophages are the main producers of PAI-2, as both B-cells and T-cells do not produce significant amounts.