U.S. blood centers that have switched to all-male plasma
to reduce TRALI cases usually say it is too early to predict the impact,
but the policy has already had a promising proving ground in Great Britain.
"Their rate of TRALI has been reduced by more than 75 percent, and their
rate of fatal TRALI has plummeted by more than 90 percent," says Dr. James
AuBuchon of Dartmouth-Hitchcock Medical Center.
Dr. Lorna Williamson of the National Blood Service
division of NHS Blood and Transplant reports that her agency's hemovigilance
program, called SHOT (Serious Hazards of Transfusion), has been monitoring
TRALI in the UK since 1996.
"In 2002, we had enough cases to do an analysis
of risk factors and components. It was clear by then that we were seeing
an excess of TRALI associated with plasma and platelets compared to red
cells, and these cases nearly always had an HLA-antibody-positive donor-all
female. That was consistent with other evidence that somewhere between
10 and 15 percent of women who have had children have HLA antibodies in
In 2002, the National Blood Service considered various
options to minimize TRALI, one of which was to ask donors for a history
of pregnancy, but with the number of other new donor questions relating
to SARS and West Nile virus, that was not viewed as a practical option.
"We next considered switching totally to solvent
detergent FFP [fresh frozen plasma] because that has a pretty good track
record, probably because donors with HLA antibodies are diluted out in
the pooling process," Dr. Williamson says. But because solvent detergent
FFP was extremely expensive, "we finally settled on a very simple strategy
to try to use only male donors for manufacture of FFP and also for suspension
of pooled platelets."
Units would be marked M or F at the donor session,
and when they came back to the blood center, the plasma from males would
be used for FFP, and the female plasma would be discarded. (Because of
variant Creutzfeldt-Jakob disease, the UK does not send plasma for fractionation
as American blood centers do.)
In making the transition, it hasn't been possible
to reach 100 percent male plasma yet, but plasma and pooled platelets
are now about 80 to 90 percent male. The results were "quite encouraging,"
Dr. Williamson says; they show a marked and steady decline in TRALI cases:
- In 2003, the baseline year, there were 36
cases of TRALI, of which 22 were highly likely or probable, and overall
eight cases from platelets and eight from FFP.
- In 2004, 23 cases of TRALI, of which 13 were highly
likely or probable, and overall four were from platelets and six from
- In 2005, 23 cases total, of which six were highly
likely or probable, two from platelets and one from FFP.
- In 2006, 10 cases total, of which three were highly
likely or probable, one from platelets and one from FFP.
The number of TRALI cases related to red-cell transfusion,
which involves far less plasma, has remained the same for all four years:
one to three per year, Dr. Williamson says.
Anne Paxton is a writer in Seattle.