Blood group genotyping

Abstract

Accurate phenotyping of red blood cells (RBCs) can be difficult in transfusiondependent patients such as those with thalassemia and sickle cells anemia because of the presence of previously transfused RBCs in the patient's circulation. Recently, the molecular basis associated with the expression of many blood group antigens was established. This allowed the development of a plethora of polymerase chain reaction-based tests for identification of the blood group antigens by testing DNA. The determination of blood group polymorphism at the genomic level facilitates the resolution of clinical problems that cannot be addressed by hemagglutination. They are useful to (a) determine antigen types for which currently available antibodies are weakly reactive; (b) type patients who have been recently transfused; (c) identify fetuses at risk for hemolytic disease of the newborn; and (d) to increase the reliability of repositories of antigen negative RBCs for transfusion. It is important to note that PCR based assays are prone to different types of errors that those observed with hemagglutination assays. For instance, contamination with amplified products may lead to false positive test results. In addition, the identification of a particular genotype does not necessarily mean that the antigen will be expressed on the RBC membrane.

O futuro da aloimunização eritrocitária

“…Nestas situações, a genotipagem de grupos sangüíneos tem mostrado ser uma excelente alternativa 7,8 e pode ser uma ferramenta útil e eficiente. O futuro da aloimunização eritrocitária, ou seja, da redução do índice de aloimunização e das reações hemo- Apesar de existirem ainda algumas questões não respondidas em relação à resposta imune a antígenos eritrocitários, acredito que a implantação de protocolos seguros e eficientes de fenotipagem e/ou genotipagem de grupos sangüíneos pode reduzir drasticamente os riscos de desenvolvimento de aloanticorpos em pacientes que recebem transfusão sangüínea.…”

“…Nestas situações, a genotipagem de grupos sangüíneos tem mostrado ser uma excelente alternativa 7,8 e pode ser uma ferramenta útil e eficiente. O futuro da aloimunização eritrocitária, ou seja, da redução do índice de aloimunização e das reações hemo- Avaliação: O tema abordado foi sugerido e avaliado pelo editor.…”

Applicability of papain solutions in immunohematology

“…Currently, there are 36 blood group systems, 38 antigens that have not yet been attributed to any system, 15 antigens distributed among 6 collections, 17 low-frequency antigens, and 6 high-frequency antigens. ( 4 – 8 )…”

“…Taking into account the expression of a blood group antigen is determined by its biochemical structure and by the position relative to the lipid bilayer, in spite of a previous enzyme treatment of red blood cells, e.g., some sensitive antigens may be destroyed or become weakly reactive, or, yet, begin having a more intense interaction with specific antibodies. ( 10 )…”

“…( 14 ) Enzyme treatment with papain (that comes from papaya), bromelain (from the pineapple), trypsin, alpha-chymotrypsin (both of animal origin), or ficin (from figs), in addition to other techniques, modifies the electronegativity, and allows the red blood cells to become agglutinable. ( 13 , 14 ) The use of proteolytic enzymes is a useful tool for characterizing an antigen of red blood cell membrane, since it has an action of fragmenting specific peptide bonds among the amino acids that make up the proteins. ( 13 , 14 )…”