HLA-targeted cell sorting of microchimeric cells opens the way to phenotypical and functional characterization

A serological and molecular study on a case of Rh blood group mosaicism

BACKGROUND

Mosaicism refers to the presence of two or more genetically different cell lines within a single individual, the majority of which are accidentally discovered through routine blood group identification. Here, we report one case of Rh blood group mosaicism in a 10-year-old Chinese male.

METHODS

Serological tests for the Rh blood group were performed via gel microcolumn tests and saline methods. Mosaic red blood cells (RBCs) were quantified via flow cytometry. The G-banded karyotype was analyzed at a 550-band resolution. Short tandem repeat (STR) analysis was used to compare the allele repeats at specific loci in DNA between blood, buccal mucosal, and hair shaft samples.

RESULTS

Mixed-field agglutination with anti-C and anti-e antibodies was identified in the gel microcolumn test. The proportion of those positive for the C antigen was 47.26 %, while that of the negative ones was 52.74 %, as calculated by flow cytometry, and the double populations were identified as DCcEe- and DccEE-phenotype RBCs by multiple centrifugations. Karyotype analysis revealed 46, XY in the proband. STR analysis revealed that additional paternal alleles were present at the D1S1656, CSF1PO, and Penta D loci.

CONCLUSION

An individual with natural Rh blood group mosaicism was identified.

Clinical relevance of feto-maternal microchimerism in (hematopoietic stem cell) transplantation

Toleration of a semi-allogeneic fetus in the mother's uterus as well as tolerance after allogeneic hematopoietic stem cell transplantation (HSCT) appear to share some immunologic concepts. The existence of microchimeric cells, and the original idea of a bidirectional cell trafficking between mother and child during pregnancy have been known for decades. Today, origins and mechanisms of persistence of microchimeric cells are intensively being elucidated. Both, the translation of the phenomenon of feto-maternal immune tolerance to donor choice or prevention of graft-versus-host disease (GvHD) in HSCT, and the implications of microchimeric cells in and for HSCT are highly intriguing. Yet, differences in detection methods of microchimeric cells, as well as in transplantation protocols impede the comparison of larger cohorts, and limit potential clinical advice. Still, matching of non-inherited maternal antigens (NIMA), which are expressed on maternal microchimeric cells, demonstrated a strong association with decreased risk for the development of acute GvHD in the context of various transplantation strategies. Despite the fact that advances in graft manipulation and immunosuppression ameliorated the safety and outcome after HSCT, NIMA-matching retained a beneficial role in selection of sibling, child, or maternal donors, as well as for cord blood units. Recent findings indicate the existence of a microchimeric stem cell niche, in which only one dominant microchimeric cell population of only one semi-allogeneic origin persists at a time. This implies that studies regarding the impact of (maternal and fetal) microchimerism (MC) on clinical outcome of HSCT should combine analysis of NIMA and direct detection of microchimeric cells from donor and recipient on the verge of HSCT to be efficiently conclusive.

Chimerism in health and potential implications on behavior: A systematic review

In this review, we focus on the phenomenon of chimerism and especially microchimerism as one of the currently underexplored explanations for differences in health and behavior. Chimerism is an amalgamation of cells from two or more unique zygotes within a single organism, with microchimerism defined by a minor cell population of <1%. This article first presents an overview of the primary techniques employed to detect and quantify the presence of microchimerism and then reviews empirical studies of chimerism in mammals including primates and humans. In women, male microchimerism, a condition suggested to be the result of fetomaternal exchange in utero, is relatively easily detected by polymerase chain reaction molecular techniques targeting Y-chromosomal markers. Consequently, studies of chimerism in human diseases have largely focused on diseases with a predilection for females including autoimmune diseases, and female cancers. We detail studies of chimerism in human diseases and also discuss some potential implications in behavior. Understanding the prevalence of chimerism and the associated health outcomes will provide invaluable knowledge of human biology and guide novel approaches for treating diseases.