Red blood cell Alloimmunization in SCD patients
During pregnancy the antibodies and antigens production levels are traced to be abnormal in
women. Such changes can affect the health of the mother and as well the new born along with
many complications during pregnancy. RBC Alloimmunization is also one such condition
which occurs due to the formation of antibodies to red blood cell antigens in the recipient from
previous blood transfusions or a pregnancy. Sometimes this condition is also traced when the
body is not exposed to foreign RBC antigens earlier before the transfusions.
The formation of antibodies in the human body differs extensively depending on the patient’s
disease, history of transfusions, pregnancy and the rate of antigens production against the donors
of different geographical locations. In order to trace the level of RBC Alloimmunization
keeping the record of the antibody and antigen rates against the transfusions is important.
Normally, the rate of red cell antibodies is estimated to be 20% or more in patients with
transfusion dependent diseases like sickle cell anemia and thalassemia etc.
Sickle-cell disease (SCD) is an autosomal recessive genetic blood disorder with over dominance,
characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases
the cells flexibility and results in a risk of various complications. The sickling occurs because of
a mutation in the hemoglobin gene during a transfusion. However, Red blood cell transfusions
have reduced despair and mortality for patients with sickle cell disease. Transfusions can anyhow
lead to RBC Alloimmunization.
Blood transfusion is an essential treatment for the patients with sickle cell disease (SCD).
However, transfusions can lead to RBC Alloimmunization with serious complications for the
patient. These antibodies produced in such conditions are often directed against antigens
expressed on RBC’s of white persons, donors of western countries. However, finding such
donors lacking those antigens can sometimes be difficult and identifying and characterizing the
antibodies can be a time consuming job causing transfusion delays.
The most serious consequence of RBC Alloimmunization in SCD patients is the risk of
developing a delayed hemolytic transfusion reaction (DHTR), which can be life taking. In many
cases, the patient's hemoglobin level falls below the pre transfusion level indicating that the
patient own RBCs are lysed in addition to hemolysis of the transfused RBCs. This condition is
known as hyperhemolysis. Additional transfusions may provoke the hemolysis and further
worsen the degree of anemia in the patients.
Not all patients develop all antibodies after exposure to transfused RBCs. This fact pertains not
only to patients with SCD but also to other transfused recipients. RBC Alloimmunization
cannot be entirely prevented except by transfusions from an identical twin or by autologous
transfusions. Preventing RBC antibody formation is also not practical for most patients and, for
man yit causes no serious complications. But prevention of RBC Alloimmunization is
important in women of child bearing age, and for some patients at risk of serious haemolytic
transfusion reactions. It is currently unknown whether RBC Alloimmunization rates differ
depending on the presence or absence of clinical complications of SCD.
In conclusion, challenges remain for the diagnosis, prevention, and management of RBC
Alloimmunization in SCD. Understanding the mechanisms and associated risk factors will aid
in developing strategies to prevent and inhibit production of antibodies in transfused patients and
to minimize its life threatening complications resulting from transfusions. Also, Immuno
modulatory therapies, such as the use of immune cell depleting agents, costimulatory blockade,
and cytokine blockade, may be effective in suppressing RBC Alloimmunization in patients.
Tracing the conditions and taking timely precautions can help to recover from such
complications during the pregnancy.