[pharmacist2030 (OP)]

I read an article which claims that fathers can't donate blood to their children with Leukemia? Is that true and why?

[evan_au]

For any blood or tissue donation (like a heart transplant), you must have a compatible tissue type, or it will be rejected.

The most familiar example is the A, B and Rh proteins in blood types. http://en.wikipedia.org/wiki/Blood_type#ABO_blood_group_system

Close relatives like parents or brothers & sisters are more likely to have compatible tissue types, but it is not guaranteed - these close relatives may carry a gene which is not carried by the recipient, which makes them incompatible.

I would expect this incompatibility to be just as likely for mothers as fathers.

Note that there are some procedures like bone marrow or liver transplants, where the transplant carries with it some aspects of the donor's tissue type, and these need fewer anti-rejection drugs after surgery.

[CliffordK]

Note that there are some procedures like bone marrow... where the transplant carries with it the donor's tissue type, and these need fewer anti-rejection drugs after surgery.

Bone marrow transplants require a very close match because the immune system cells are also transplanted with the blood cells, and could potentially recognize the recipient's body as foreign.  However, I don't believe that anti-rejection drugs are given on a long-term basis like with other transplants because the the transplant carries with it the immune system.

Identical twin bone marrow donors, however, are not generally used because a moderate amount of graft vs host disease is actually beneficial to fighting the leukemia.

Families, of course, would be good for marrow donor searches.  However, I believe that siblings who receive antigens from both parents have a greater likelihood of a match than the parents who might have only half the antigens.

As Evan mentioned, a blood donor requires fewer antigens than a bone marrow match, so parents are a good possibility. 

[RD]

Mother's immune system has tolerated the child before in-utero ...

We analyzed the outcome of 118 patients who received transplants for acute leukemia in 2 centers. Patients received highly T cell–depleted haploidentical grafts after myelo-ablative conditioning. Five-year event-free survival was better in patients who received transplants from the mother than from the father (50.6% ± 7.6% vs 11.1% ± 4.2%; P < .001). ...

Better outcome of mother-to-child transplantation may be the result of the maternal immune system exposure to fetal antigens during pregnancy.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2962448/