RE: Blood Irradiation for GVHD

["Knapp, Steven J." <Steven.Knapp@med.va.gov>]

Graft-Versus-Host-Disease (GVHD):

In order to provide you with more information concerning the irradiation of
blood products, I have taken excerpts from the FDA (Center for Biologics
Evaluation & Research) document titled "Recommendation Regarding License
Amendments and Procedures for Gamma Irradiation of Blood Products" published
July 22, 1993.

GVHD occurs when viable T lymphocytes in transfused blood or blood
components engraft, multiply and react against tissues of the recipient.
GVHD may be seen when blood components are transfused to immunocompromised
recipients (bone marrow transplant patients), patients with malignancies
receiving aggressive chemotherapy, persons with congenital immune deficiency
syndromes and non-immunocompromised recipients following transfusion of
blood donated by family members.

Methods of producing leukocyte-reduced whole blood and components (including
washing, filtration and centrifugation) reduce the number of viable T
lymphocytes but do decrease the risk of GVHD as effectively as irradiation.

Gamma irradiation of blood products has been in routine use in conjunction
with bone marrow transplantation for approximately 25 years.  Clinical
observation over approximately 30 years during which transfusion of
irradiated blood has been practiced has resulted in only two case reports of
GVHD in recipients of irradiated blood products and these cases involved use
of suboptimal irradiation doses.

The irradiation dose delivered should be 2500 cGy targeted to the central
portion of the container and 1500 cGy should be the minimum dose at any
other point.  Studies have shown red cells irradiated within 24 hours of
collection maintain satisfactory viability up to 35 days.  Units of
irradiated blood cells contain approximately twice as much extracellular
potassium indicating that irradiation increases the rate of potassium
leakage.  Units of irradiated red blood cells contain more cell-free
hemoglobin.  Units of irradiated platelets have shown no post-irradiation
change in function.

Steve Knapp, Ph.D.
Medical/Health Physicist
VA Medical Center Augusta, GA
steven.knapp@med.va.gov

> ----------
> From: 	Carbaugh, Eugene H[SMTP:gene.carbaugh@pnl.gov]
> Reply To: 	radsafe@romulus.ehs.uiuc.edu
> Sent: 	Tuesday, March 16, 1999 1:00 PM
> To: 	Multiple recipients of list
> Subject: 	Blood Irradiation for GVHD
> 
> 
> I'm showing my ignorance.  If healthy blood is irradiated to prevent Graft
> vs.
> Host Disease, what is the impact on the healthy cells in the blood.  I
> guess
> fundamental to my question is a need to better understand the nature of
> GVHD.
> Presumably the reason for transfusion is to replace lost or dysfunctional
> red
> cells, platelets, white cells, etc, until the body can resume production
> of its
> own.  Is the blood irradiation dose sufficiently high to impact the
> desired
> cells, and if so, to what extent?  
> 
> Gene Carbaugh, CHP
> Internal Dosimetry
> Pacific Northwest National Laboratory
> gene.carbaugh@pnl.gov
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