[Frequency of minor histocompatibility antigens among Chilean blood donors]. / Frecuencia génica de antígenos menores de histocompatibilidad en la población chilena y estimación de sus efectos inmunológicos en el trasplante alogénico de progenitores hematopoyéticos.

BACKGROUND: Minor histocompatibility antigens (mHAgs) play a critical role in the immune responses associated with allogeneic stem cell transplantation, such as graft versus host disease (GVHD) and graft-versus-tumor (GVT). AIM: To determine the gene frequencies of the mHAgs HA-1, HA-2 and HA-8 in Chilean Blood Bank donors. MATERIAL AND METHODS: Blood from 192 blood donors was analyzed. The presence of haplotype HLA-A*02 was determined by flow cytometry. The frequency of mHAgs was determined by allele specific polymerase chain reaction in genomic DNA. RESULTS: Sixty one participants were carriers of the haplotype HLA-A*02. The relative allele frequency HA-1H was 45%, HA-Ir 55%, HA-2V 80.6%, HA-2M 19.4%, HA-8R 49.8% and HA-8P was 50.2%. Based on mHAgs disparity between HA-1, HA-2 or HA-8, the probability to generate a GVT response in HLA-A*02 individuals was 40%. CONCLUSIONS: The mHAgs frequency in Chilean population is under Hardy-Weinberg equilibrium and they are similar to those of other ethnic populations in the world.

Frecuencia génica de antígenos menores de histocompatibilidad en la población chilena y estimación de sus efectos inmunológicos en el trasplante alogénico de progenitores hematopoyéticos / Frequency of minor histocompatibility antigens among Chilean blood donors

Background: Minor histocompatibility antigens (mHAgs) play a critical role in the immune responses associated with allogeneic stem cell transplantation, such as graft versus host disease (GVHD) and graft-versus-tumor (GVT). Aim: To determine the gene frequencies of the mHAgs HA-1, HA-2 and HA-8 in Chilean Blood Bank donors. Material and Methods: Blood from 192 blood donors was analyzed. The presence of haplotype HLA-A*02 was determined by flow cytometry. The frequency of mHAgs was determined by allele specific polymerase chain reaction in genomic DNA. Results: Sixty one participants were carriers of the haplotype HLA-A*02. The relative allele frequency HA-1H was 45%, HA-Ir 55%, HA-2V 80.6%, HA-2M 19.4%, HA-8R 49.8% and HA-8P was 50.2%. Based on mHAgs disparity between HA-1, HA-2 or HA-8, the probability to generate a GVT response in HLA-A*02 individuals was 40%. Conclusions: The mHAgs frequency in Chilean population is under Hardy-Weinberg equilibrium and they are similar to those of other ethnic populations in the world.

Respuesta inmune contra antígenos menores de histocompatibilidad en el trasplante alogénico de progenitores hematopoyéticos / Immunologycal response under antigens hematopoietic stem cell transplantation

Patients who receive allo hematopoietic stem cell transplantation (SCT) could develop graft versus host disease and/or graft versus tumour effect. These immunological responses can happen even with perfect fully HLA matched haematopoietic stem cells. Moreover, the engraftment of the donor’s cells depends on the immunological conditions of both donor and recipient. The development of alloreactivity occurs in the context of the polymorphisms of the human genome, these genomic differences results in proteins with antigenic properties which trigger immune responses. Considering this, the SCT is a powerful tool to heal the patient disease, because all of them become chimeras. In other words, into individuals with two different genomic sets, which will develop a strong immunological response that cannot exist in natural conditions.