Why do some people require compatible platelets?

Patients that have built antibodies against HLA or platelet antigens require HLA- or platelet antigen-compatible platelets.  If these individuals are given incompatible platelets, their antibodies can rapidly destroy the transfused platelets.  If a patient’s platelet count decreases immediately following transfusion, it may be a sign that the patient requires compatible platelets.  Unfortunately this is not always a clear sign as there can be other reasons why a patient’s platelet count does not increase after transfusion such as chemotherapy, active bleeding, or fever.

What if I have friends or relatives that would like to donate platelets for me? 

The best approach when friends or relatives would like to donate is for them to make a donation appointment with the INBC hemapheresis department.  When the product is drawn, extra samples will be drawn for HLA typing.  If the donor is HLA compatible, that product may be given to the patient and the donor may be recruited for ongoing support.  If the donor is not HLA compatible, the product will be given to another patient in need.  Make an Online Appointment.

What is a PRA?

PRA stands for Percent (or Panel) Reactive Antibody.  The PRA is expressed as a percentage and is used as a rough estimate of what percent of donors a person will NOT be compatible with.  In other words, a person with a PRA of 40% will NOT be compatible with roughly 40% of possible donors.

Can my PRA change?

Yes. Typically a PRA is highest following a sensitizing event (pregnancy, transfusion, or transplant) and decreases with time.  Patients who are not sensitized should consistently have a PRA of 0%

If I am the same ABO type as my sibling, does this mean we will have the same HLA type?

No.  Although the genes that code for the various HLA antigens are inherited together, the genes that code for your ABO type are not inherited with your HLA antigens.

What are the chances of being a match with my immediate family?

An individual will inherit half of their HLA antigens (called a haplotype) from each of their biological parents.  If the parents share any HLA antigens with each other, it is possible for their child to share more than a haplotype with the parents.  For siblings, there is a 1 in 4 chance of being HLA identical, a 1 in 4 chance of being completely non-identical, and a 1 in 2 chance of sharing a haplotype.

What are the chances of being a match with more distant relatives or friends?

The likelihood of being HLA identical gets lower for more distant relatives.  A first cousin has a 1 in 16 chance of being HLA identical.  The chances of being a match with unrelated individuals depend on the frequency of your HLA antigens in the population.