Hmm

The plasma used in transfusions will soon come almost exclusively from men.

[B]lood banks are beginning to separate out women's plasma — the liquid part of blood — in an effort to fight a mysterious lung injury that has become the nation's leading risk from transfusions.

…No one knows exactly what causes TRALI ["transfusion-related acute lung injury"]. But certain immune cells carried by women who have been pregnant are emerging as a chief culprit, cells called antibodies that mothers-to-be produce in reaction to their fetus' foreign father cells.

The antibodies do no harm to mother, baby or the vast majority of people who encounter them in a transfusion. To get TRALI requires what Celso Bianco of America's Blood Centers calls "a horrible coincidence" in which the transfusion recipient has white blood cells that just happen to recognize and clash with the donor's antibodies.

TRALI kills about 15 people annually, out of 150 or so whose specific circumstances converge in that "horrible coincidence." And the antibodies specific to women who have been pregnant are not TRALI's only trigger; if they were, "the lung ailment would be common, too. Instead it's rare, occurring about once per 5,000 units of transfused blood products. Something has to 'prime' the lungs to be susceptible." So, it's conceivably possible at some point to isolate the priming factors and deal with those so women's plasma can still be used in transfusions.

But in the meantime, men's plasma only. Scientists are worried that women will hear this and feel they don't need to donate blood anymore, but I can't help thinking of the plasma center my aunt used to manage, which was disproportionately populated with low income women who were selling their plasma to feed themselves and their kids. You can't sell your blood, you see; only your plasma.