Thirteen lots of plasma protein fraction made by one manufacturer were implicated in 23 recent reports of hypotension in surgical patients. Four of these patients required resuscitation after rapid administration of the product in the postoperative period. All implicated lots had prekallikrein-activator activity but low levels of bradykinin and kallikrein. The prekallikrein activator was identified as Hageman-factor fragments by molecular weight (35,000 as estimated by gel chromatography), isoelectric point (4.2 to 4.4), and inhibition by antibody to Hageman factor. These data suggest that Hageman-factor fragments are potent hypotensive agents, presumably because they trigger the generation of bradykinin in recipients. Prekallikrein-activator activity, usually at levels lower than those in the initial 13 implicated lots, was frequently detected in plasma protein fraction made by other manufactures. Several of these lots were associated with additional reports of hypotension. Prekallikrein-activator activity rarely occurred in albumin.

These findings and the recipient's clinical history support a causal relationship between the implicated AHF product and B19 infection in this recipient. The seronegative patient became infected after receiving 2x10(4) IU (or geq) of B19 DNA, which was present in this S/D-treated, high-purity AHF product.