HLA MAPPING

Hi everyone

I have registered my daughter to one of the thalessemia society Last sunday  and the doctor their has told us to go for HLA Mapping and after that go for BMT if it is successful . as you all know my younger daughter is now 7 months old . can any one tell me what is this HLA test . the cost in AIIMS as per doctor is 15000 rs for the whole family.

With thanks & regards
Rupali

HLA (Human Leukocyte Antigen) compatibility is tested so that there are no rejection issue with donor's Bone Marrow for the body's cells (probably Leukocytes which fight external infection) so that they don't recognise it as a foreign object and tries to kill it off. Similarly the Bone marrow also tries to react with the body cells. This is known as Graft versus host disease (GVHD). This test ensures that there is a minimal chance of GVHD.

This is just a simple explanation; there are more complicated factors involved.

Thanks sajid

Can i get some more informamtion on it  adn canyou please tell it is safe for person who is giving bonemarrow and for the person who is receiving it .I just want to ask what is the successrate . As you are thalessemic major why haven't you gone for it .

with thanks & regards
Rupali

Well, I don't really know what complexities are involved in HLA type matching all I know is that it requires a pretty good match with all or most of the attributes matching. I got HLA tested with my family for a BMT but failed to get a good match with my family.

BMT has a risk of GVHD even with a good match so in the end it all ends up with your luck. The process is somewhat painful for the donor as it involves extraction of the marrow directly from the hollow bones like the femur (thigh) etc. It is quite painless for the recipient as it is transplanted just like a blood transfusion. However the existing system needs to be disabled or killed with chemotherapy which also disables the immune system for a while and in that time the patient is most vulnerable to infection.

So, it is a risky process and needs to be discussed thoroughly with your doctors.

Using peripheral stem cells instead of bone marrow eliminates the pain and small danger to the donor, as the stem cells are taken from the blood, rather than injecting a needle into the bone to extract bone marrow.

Even with 100% HLA matching, GVHD occurs because the recipient has previously been exposed to antigens from the transfused blood. The more transfusions a patient has had, the higher the risk of GVHD. A new trend seen in the US, is to only provide perfectly matched blood from the very first transfusion. This greatly reduces any blood reactions, provides more compatible blood, and would also keep patients as better candidates for BMT's.

Andy,

When you say perfectly matched blood,does that mean blood from a perfectly HLA matched donor? but that would be very rare,as finding a complete match itself is very difficult.

ZAINI.

Hi Rupali

Hope you daughter is doing good.
I really dont know much about BMT and HLA mapping but you can go through following site and i hope most of your doubt will be cleared

http://www.healthsystem.virginia.edu/uvahealth/peds_oncology/bonetran.cfm

http://cpmcnet.columbia.edu/dept/medicine/bonemarrow/bmtinfo.html

Good Luck

Harminder

The blood matching that I referred to is the matching for the most common 5 antibodies from the very first transfusion and on. By matching these antibodies, the formation of new antibodies in the patient is almost completely eliminated.

This study dealt with sickle cell but its findings apply with thalassemia also.

http://cbbsweb.org/enf/2001/sickletx_match.html

A recent report by Vichinsky et al in Transfusion Sept., 2001 showed that routine transfusion of phenotype-matched RBCs (matched only for ABO, D, C, E and K) can reduce the risk of new antibody formation in sickle cell anemia patients. What is interesting is that a large percentage of alloimmunizations are preventable by matching for such a limited number of antigens.

From http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=11552063&dopt=AbstractPlus

This is the first multicenter study to show that extended RBC phenotyping can be implemented nationwide. Compared to studies, the alloimmunization rate dropped from 3 percent to 0.5 percent per unit, and hemolytic transfusion reactions dropped by 90 percent.

The foreign antibodies introduced in many transfusions lead to many problems and an early death to transfused blood cells. The response of the immune system to these antibodies can cause many problems, including increased transfusion frequency. More efficient typing is fairly easy to do but has not been yet applied even in many areas of the US. Thal patients and their parents around the world need to demand better techniques for providing blood that is safe in more ways.