Genomic analysis of ABO chimeras and mosaics using hematopoietic colony-derived DNA

Blood doping in athletes--detection of allogeneic blood transfusions by flow cytofluorometry

Athletes may undergo blood transfusion to increase their red cell mass and the oxygen carrying capacity of their blood in order to confer a competitive advantage. Allogeneic transfusions are normally mismatched at one or more minor blood group antigens. The most sensitive and accurate method known to detect this form of blood doping is flow cytometry. Low percentages of antigen-positive and antigen-negative red blood cells (RBCs) can be quantitated using suitable specific alloantibodies and careful analysis. By testing blood samples taken at various times, a reduction in the percentage of a minor population of RBCs will indicate transfusion has occurred.

Chimerism in the immunohematology laboratory in the molecular biology era

Dual or multiple cell populations, induced by chimeras, have been the subject of many studies. This long-standing fascination with chimeras has revealed a good deal of knowledge about human inheritance. Although historically most chimeras were caused by natural events, certain current medical intervention therapies are increasing the number of situations that can lead to a mixed cell population, that is, the chimeric condition, in humans. Medical therapies such as transfusion, stem cell transplantation, kidney transplantation, and artificial insemination induce temporary and sometimes permanent chimeras. Such natural or therapeutically induced presentations of chimerism can present challenging issues to the clinical immunohematology laboratory with regard to interpretation of results and subsequent patient management. The purpose of this review was to highlight some of these chimeric states and hypothesize how testing DNA from various tissues can cause apparent discrepancies between phenotype and genotype results.

Blood group chimerism

PURPOSE OF REVIEW

With improved methods for detecting chimeras and growing numbers of stem cell transplantations, blood group and other forms of chimerism are observed with increasing frequency. This review will focus on the state of science and new insights into the multifaceted subject of blood group chimerism.

RECENT FINDINGS

Recognition that the immune system tolerates chimeric cells under certain conditions has led to efforts to elucidate related immune-modulating processes. The chimeric state following transplantation of hematopoietic stem cells, as well as after solid organ transplantation, is of special interest. Also, chimerism is considered to be a potential trigger for certain autoimmune diseases. Natural chimerism is more frequent than previously recognized. Using improved laboratory techniques, investigators can often trace chimeric tissues to their origin. New therapeutic strategies have been applied after stem cell transplantation depending on the chimeric state. Also, recent research has resulted in methods for determining chimerism in maternal peripheral blood that reflect fetal blood type and certain congenital diseases.

SUMMARY

The subject of human chimerism has evolved from a curiosity of nature to an important field of research and, potentially, holds the key to advancing our understanding of the fundamental mechanisms of immune tolerance.