PR Newswire - November 1, 1995

Cytomegalovirus (CMV) is a common infection that affects white blood cells, or leukocytes. It poses little risk to most healthy people but can produce life-threatening pneumonia and complications for patients with surpressed immune systems who need transfusions. Patients include marrow or solid organ transplant patients, all newborn children who need transfusions, and certain AIDS patients.

The study's results are welcome news to blood banks faced with shortages of CMV-negative blood due to the ever-increasing demand stemming from the spread of AIDS and the increasing use of transplantation. It is especially significant for those blood banks in parts of the United States and abroad where very few CMV-negative donors are available.

Researchers at the Hutchinson Center and the University of Minnesota, in collaboration with the Puget Sound Blood Center, the University of Minnesota Blood Banks and the St. Paul American Red Cross, tracked 502 marrow transplant patients over a four-year period.

Half of the patients were randomly assigned to receive blood transfusions through a special filter device and half were given screened (tested) blood. The results showed that filtering blood for the virus was as effective as testing donor blood for the presence of the virus.

"This is the first time the blood supply, which can carry a number of potentially dangerous infections, has been rendered safe from a specific infection (CMV) by filtration," says lead author Dr. Raleigh Bowden, acting director of the Infectious Diseases Program at the Center.

"This has enormous impact because, unlike hepatitis or HIV, the results of this study have shown that blood from a seropositve blood donor can be safely used after filtration in any patient without the risk of transmitting CMV. Because the study showed that filtrations is as effective as CMV-screening for the prevention of transfusion-acquired CMV infection, either technique can be used depending on the availability of screened blood and the cost of either method."

The reason Bowden is so confident in making the recommendation is that marrow transplant patients face much more exposure to transfusion-transmitted CMV than any other type of patient.

The average marrow transplant patient receives 23 units of red blood cells and 120 units of platelets (clotting cells) over the course of treatment. They also are as immunosuppressed, if not more so, as patients in any other risk group.

The National Institutes of Health-funded study will relieve the pressure on blood banks that previously had to maintain sufficient quantities of CMV-free blood for transfusions in these patients.

"It is nice from the blood bank perspective to have the choice of filtering or screening. It is very easy to run out of sero-negative (CMV-free) donors" says Dr. Merlin Sayers, director of transfusion surveillance for the Puget Sound Blood Center and a co-author of the study.

"If you have two marrow transplant patients and two liver transplant patients who are all CMV-negative, those four patients could easily deplete a blood bank's supply of screened blood because of the quantity of blood those types of patients require," he says.

The study was the culmination of 12-year collaborative study of the problem of transmitting CMV disease through blood transfusions by the Hutchinson Center and the Puget Sound Blood Center.

In the 1970s and early 1980s, physicians knew that, if patients had never had CMV, they had a 40 percent chance of being infected from a blood transfusion. At the time, however, they could not do anything to prevent it.

In 1986, Bowden's team showed that testing blood for the presence of CMV, and giving only units that tested negative, reduced infections in marrow transplant patients to 2 percent.

But screening blood is cumbersome and costly for blood banks. It mean they must store and track separate inventories of units of blood -- one supply that tests negative for the virus and one that either tests positive or is not tested.

In some parts of the country, including New York, most people have been exposed to CMV, making the cost per unit of CMV-safe blood very high, because the yield from screening is so low.

The study results also will affect the small number of AIDS patients who have never had CMV and need to receive blood transfusions. CMV can cause retinitis in these patients, which can lead to blindness. These patients previously required screened blood, and can now safely receive filtered transfusions.

The study, however, has little effect on blood bank screening for hepatitis or other infectious diseases since it is, thus far, not possible to filter those diseases out of blood.

Blood banks will still have to screen for those diseases, which is why blood banks never have enough blood. It is difficult to find willing donors who are negative for all infectious diseases.

"All of this would be a moot point were it not for people who take it upon themselves to donate blood," Sayers says. "Without those people there would be no donor blood, nor even the ability to conduct this study."

Besides Bowden, Center investigators included Monica Cays, Gary Schoch and Drs. Meera Banaji and Lloyd Fisher. Other co-authors included Dr. Sherrill Slichter and Sayers of the Puget Sound Blood Center, and Drs. Wes Miller, Dan Weidsdorf, Robert Haake, Jeffrey McCullough, and Kevin Welk of the University of Minnesota.

CONTACT: Susan Edmonds of the Fred Hutchinson Cancer Research Center, 206-667-2896; or Keith Warnack of the Puget Sound Blood Center, 206-292-6511/ 03:00 EST

Copyright (c) 1995/PR NewsWire. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Permissions Desk, PR Newswire, 810 Seventh Avenue, New York, NY 10019.
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