What is an immune passport and why is it difficult to find an immunological counterpart?

Each of us is unique: fingerprints, the shape of the ears, the smell. However, this uniqueness is not only external, our cells are also unique

What is an immune passport?

  • This is a unique combination and set of protein molecules on the cell surface called Human Leukocyte Antigen (HLA antigens). It is called leukocyte, because HLA proteins are most pronounced on these blood cells
  • The task of HLA proteins is to recognize foreign cells (bacteria, cancer cells) or viruses and to launch an immune response, a rejection program to remove them from the body. It works during transplantation

It is tissue compatibility, that is, the correspondence of HLA proteins between donor and recipient, is so important for engraftment

HLA antigens are most pronounced on nucleated cells, especially leukocytes. Bone marrow is blood-forming cells, in particular, early and mature forms of leukocytes. Therefore, bone marrow transplantation requires the strictest correspondence between the donor and the patient, even in comparison with the transplantation of other organs (heart, liver, kidneys)

Why is it difficult to find an HLA twin?

  1. Variability
    The complex of HLA antigens in humans is very variable. And the chances of finding a bone marrow donor worldwide are from 1 in 1000 to 1 in 1 000 000
  2. Multinationality
    It is extremely difficult to find a compatible donor for multinational families
  3. Compatibility
    Only identical twins can be complete immunological twins. In varying degrees, close relatives are compatible. An interesting feature of the HLA antigen system is that if a couple turns out to be ideal donors for each other, the children in this couple may not

How is the search for a suitable donor carried out?

Anyone can determine his immune passport. It is only necessary to donate blood for HLA-typing. There is an international registry that contains information about the HLA phenotype of healthy people who would like to save someone’s life by becoming a bone marrow donor. If transplantation is required, patient’s immunological passport data is entered into this registry in order to search for compatible bone marrow or cord blood from state biobanks. And if there are matches, the graft is sent to the clinic for transplantation

With incomplete immunological compatibility, it is safer to use cord blood, rather than bone marrow, because the risk of obtaining immunological complications is much lower. Why does it happen? The reason is that the HLA antigens are less expressed on hematopoietic cord blood cells

Saving your baby’s cord blood will give him a calm future, the confidence that, if necessary, he has a perfectly compatible hematopoietic cell transplant that will save his health and life