Liquid purification or separation – Processes – Separating
Reexamination Certificate
1997-05-21
2001-03-06
Kim, John (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S650000, C210S651000, C210S782000, C210S787000, C435S002000, C604S006030
Reexamination Certificate
active
06197207
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the transmission of diseases. More specifically, the present invention relates to the transmission of spongiform encephalopathy diseases through blood products.
In a variety of therapies, such as transfusions and transplants, body fluids, especially blood components, such as red blood cells, platelets, plasma, and bone marrow, are infused from one or more individuals into a patient. The development of such treatments provide therapies, some of which are life-saving, that cannot otherwise be provided. However, due to the risk of transmission of certain disease states, there may be potential risks with such therapies.
Unfortunately, it is also known that a number of disease states can be transmitted through the infusion of blood products. For example, it is known that blood can carry infectious agents, such as hepatitis virus, human immunodeficiency viruses (an etiological agent for AIDS), cytomegalo virus, Epstein Barr virus, and herpes virus. Much recent effort has been devoted to eliminating the risk of the transmission of hepatitis and acquired immune deficiency syndrome (AIDS) through blood and blood products.
In certain areas of the medical community, recent attention has been focused on transmissible spongiform encephalopathies (TSE). TSE diseases are progressive, lethal central nervous system disorders that are characterized by localized anatomical changes in the brain. These changes consist of vacuoles and protein deposits.
TSE diseases occur in both humans and animals. These neurodegenerative diseases have long latency periods. In humans the latency period can reach up to 30 years. When the disease manifestations finally begin to occur, death usually results within 2 to 4 months; due to the loss of central nervous system function.
TSE diseases can occur: 1) spontaneously; 2) through inheritance; or 3) by iatrogenic exposure to contaminated material. It is believed that the infectious particles responsible for TSE diseases are composed predominantly or perhaps even solely of protein. These proteins have been referred to as prions. It is believed that the infectious prion particles are composed largely, if not entirely, of an abnormal isoform of a normal glycoprotein which is anchored to the external surface of cells. The infectivity of prions has an unconventional property of being unusually resistant to various physio-chemical procedures.
Although TSE diseases have been known for some time, much recent attention has been focused on a new variant of TSE diseases. In March, 1996 Creutzfeldt-Jakob (vCJD) was officially reported. The variant CJD is so called because of the younger ages, than the classical CJD, in which it occurs. Additionally there are also some clinical and pathological differences between the diseases.
There has been some discussion whether there is a link between bovine spongiform encephalopathy (“mad cow disease”) and VCJD. Circumstantial evidence suggests exposure to BSE may be the most likely hypothesis for the emergence of vCJD.
Because iatrogenic transmission has been demonstrated with transmissible spongiform encephalopathies including human CJD and vCJD, there may be a question of whether or not such transmissions can occur through blood products. Accordingly, there may be a need for reducing the potential of a risk of the transmission of TSE diseases through blood and/or blood products.
SUMMARY OF THE INVENTION
The present invention provides a method for reducing the risk of the transmission of TSE through blood or blood products. The invention is based on the surprising discovery that the prions that cause TSE reside in the leukocytes. Through the intact removal of the leukocytes the risk of transmission of TSE through blood, blood components, or products made therefrom can be eliminated.
To this end, the present invention provides a method for at least reducing the potential risk for the transmission of transmissible spongiform encephalopathy through blood products comprising the step of removing, intact, substantially all leukocytes that are present in the blood product, or an intermediate of the blood product, prior to administering the blood product to a patient.
In an embodiment, the leukocytes are removed through filtration.
In an embodiment, the leukocytes are removed through centrifugation.
In an embodiment, the blood product is chosen from the group consisting of: whole blood; red blood cell concentrate; plasma; platelet concentrates; pooled platelet concentrates; albumin; gamma globulin; coagulate factors; and cryo-precipate.
In an embodiment, the leukocytes are removed using a size exclusion filter. In a preferred embodiment, the filter comprises at least three membrane filter.
In another embodiment of the present invention, a method of processing blood plasma to prevent the transmission of transmissible spongiform encephalopathies disease is provided. The method comprises the step of removing to a level of not greater than 1 cell/&mgr;l leukocytes that may be present in the blood plasma without lysis of leukocytes.
In a still further embodiment of the present invention, a method for preparing a blood product so as to reduce the risk of the transmission of prion transmissible diseases through the infusion of the blood products is provided. The method comprising the steps of: collecting blood plasma; removing intact leukocytes from the blood plasma product without causing the lysis of leukocytes; and preparing a blood product from the blood plasma.
Accordingly, an advantage of the present invention is to reduce the risk of the transmission of TSE diseases.
Moreover, an advantage of the present invention is to reduce the risk of transmission of TSE diseases through blood and blood products.
Still an advantage of the present invention is to reduce the risk of transmission of prions through blood or blood products.
Further, an advantage of the present invention is to provide a method for insuring that TSE diseases are not transferred through the use of blood and/or blood products.
These and other features and advantages of the present invention are set forth in detail below in the detailed description of the presently preferred embodiments.
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Chapman John
Fisher Jerry
Barrett Robert M.
Baxter International Inc.
Kim John
Rockwell Amy L. H.
Serewicz Denise M.
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