ASCLS - Laboratory Testing - Chemistry Tests

lmmunohematology (Blood Bank)

Apheresis

During apheresis blood is removed from the patient or donor. Blood is made up of parts including red blood cells, white blood cells, platelets and plasma. One of the parts of the blood is removed and the rest of the blood is returned to the patient or donor. Apheresis may be performed to collect a specific blood component from a donor for transfusion or it may be performed as a form of therapy for some diseases. The principle used to separate the blood is known as centrifugation. When blood is centrifuged (spun like clothes in a washer) the heavier parts of the blood are separated from the lighter parts in layers just like the clothes cling to the side of the wash tub and the water is removed in a washer. The apheresis machine is able to select the layer needed and the reminder is returned to the donor or patient.

Apheresis for Blood Donation

Apheresis may be used to provide blood components for transfusion. Donors must meet all of the requirements for blood donation as well as additional screening criteria depending on the blood component being collected. A person's blood volume is related to their size and very small people may have too small a blood volume to donate plasma or red blood cells.

Platelets can be collected by apheresis. In some cases, patients may not be able to make platelets or have the intended rise in platelet count after a transfusion and special donors whose platelets are tested to be compatible (the testing is called crossmatching) or whose platelets contain the same HLA matched antigens may be needed.

Some donors provide plasma while others may provide red blood cells by apheresis donations. Apheresis Red Cell donations were first used for autologous (giving your own blood so you can get it back later) and directed donations (donating for a specific person) but are becoming widely used for routine donations

An apheresis donation will take approximately 2 hours.

Apheresis for Stem Cell Collection

The cells needed by cancer patients who have been treated with high dose chemotherapy and/or radiation may need to have the cells that produce the blood (stem cells, progenitor cells) restored to them. Some cancer patients are able to give their own stem cells before treatment for infusion after treatment - this is called an autologous transplant. It may b7e necessary to have several apheresis cell collection procedures over a two or four day period. It may take two to four hours per procedure.

Some patients must have cells from a specially selected donor. This donor may take special medication to increase the number of stem cells in their blood. The donor may be able to provide enough stem cells in a single donation of two to four hours, or may need to donate on more than one day. The procedure may last from two to four hours.

More information on cellular therapy can be found at ttp://www.celltherapy.org/cytotherapy.htm. For more information about being a stem cell donor contact your local blood center or The National Marrow Donor Program http://www.marrow.org/.

Apheresis as Therapy

The American Association of Blood Banks (AABB) http://www.aabb.org and the American Society for Apheresis (ASFA) http://www.apheresis.org/diseases.html have developed guidelines listing diseases that are treated by apheresis. Not all patients respond well to apheresis and apheresis has not been found to be effective in treating some diseases. Insurance carriers may not reimburse the cost of treatment unless the apheresis has been shown to be an effective treatment. The list below is a selected list prepared from the medical literature.

	AABB	ASFA
Red Cell Exchange
Red Cell Removal - ABO incompatible bone marrow transplant		1
Hemolytic transfusion reaction	3
Sickle cell anemia	1	1

Plasma Exchange
AIDS	4
Amyotrophic lateral sclerosis(Lou Gherig's Disease)	4	4
Aplastic anemia	4	3
Cancer		3
Chronic inflammatory demyelinating plolyneuropathy (CIDP)	1	1
Coagulation factor inhibitors	3	2
Goodpasture's syndrome	1	1
Guillain-Barre syndrome	1	1
Hemolytic uremic syndrome (HUS)	2	3
Hepatic (liver) failure - acute	4	3
Hyperviscosity	1	1
Idiopathic thrombocytopenic purpura (ITP)	4	3
Mysthenia gravis	1	1
Posttransfusion purpura	1	1
Psoriasis	4	4
Refsum's disease (phytanic acid)	1	1
Renal transplant rejection	4	4
Rheumatoid arthritis - plasma exchange	4	4
Thrombotic thrombocytopenic purpura (TTP)	1	1
Cell Reduction
Cutaneous T-Cell lymphoma (also photopresis)	2	1/2
Leukemia with extremely high with count	1	1
Multiple Sclerosis (or plasma pheresis)	3	4
Rheumatoid arthritis - cell reduction	3	3
Thrombocytosis (too many platelets)	1	1

Standard therapy
May be useful along with other therapy
Inconclusive evidence
Not effective in controlled clinical trials

Some patients require the plasma (liquid) part of the blood to be replaced. This is known as plasmapheresis. Other patients such as sickle cell anemia patient required their own red cells be removed and replaced with donor red cells. Still other patients such as some leukemia patients may have too many white blood cells or platelets. Cell reduction is called cytopheresis.

When a large amount of plasma is taken out, the volume of plasma removed is replaced by saline solutions, albumin, or plasma.

In order for the cells and plasma to be well separated there must be a good flow of blood from the patient to the apheresis instrument. It may be necessary to place an indwelling tube (catheter) in the patient.

It may be necessary to change the timing, dose and type of drugs used by the patient as some drugs are removed during the apheresis process.

The risks of apheresis procedures include

bleeding
tingling of lips due to the anticoagulant
feeling cold (hypothermia)
hyperventilation
drop in blood pressure
infections
damage to the red cells processed in the equipment
allergic reactions
respiratory distress
clotting

HLA for consumerS

The HLA system is involved with the human body's immunity or defense. The system is a first line of defense that helps our bodies to recognize when something foreign is introduced into it. For example, when a transplant of bone marrow, a kidney or liver is performed, it is the HLA system that tells the body something foreign is present. When physicians talk about finding a "match" when looking for an organ donor, they mean not only an ABO blood type match, but also an HLA system match.

Some of the problems that physicians have to contend with involving the HLA system are:

(1) Graft-versus host disease in organ transplant recipients.
(2) Inability of platelet transfusions to work for a patient.
(3) Reactions following the transfusion of platelets and red blood cells.

HLA typing is used:

(1) To determine if donors and recipients are a good match prior to bone marrow or organ transplant or platelet transfusion.
(2) In parentage testing. HLA typing alone can exclude about 90% of falsely accused men.
(3) In forensic testing to identify individuals from very small pieces of tissue, hair or cells.

There is some evidence that HLA types are associated with certain diseases. Scientists are not sure why this is so. Many of the associated diseases are what are called "autoimmune " diseases, or diseases where an individual's own immune (defense) system attacks itself. Some of these diseases are: ankylosing spondylitis, narcolepsy, type I diabetes, multiple sclerosis, rheumatoid arthritis and Grave's disease.