Influence of the Rh phenotype on the D antigen expression

LUJÁN M; TRUCCO BOGGIONE C; MATTALONI S; ENSINCK A; RACCA L; BIONDI C; COTORRUELO C

Los Cocos

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Sociedad Argentina de Inmunología

Alloimmunization against the D antigen depends on level of expression of the RhD polypeptide in the red blood cell membrane. The aim of this work was to analyze the D antigen expression in RhD positive samples with different Rh complete phenotype by flow cytometry. The Rh phenotype on erythrocyte suspensions was determined by hemagglutination using monoclonal antibodies anti-D, C, c, E and e. RhD positive samples and controls (RhD negative) were incubated with monoclonal IgG anti-D and then with anti-human IgG labeled with Alexa 488. One hundred thousand events were acquired and data were analyzed with the FACSDiva software. Statistical analysis showed that the median and interquartile range for the variable median of the fluorescence intensity associated with the D antigen expression were: samples with Ccee phenotype (n=9) 10816,0 ± 3430,0; CCee (n=8) 14731,0 ± 11354,5; ccEe (n=6) 16906,5 ± 8546,0; CcEe (n=9) 20508,0 ± 13619,0 and ccEE (n=2) 28267,0 ± 686,0. The value obtained was significantly higher in ccEE samples when compared with Ccee samples (p<0,05, Kruskal-Wallis and Dunn test). Samples with CCee, CeEe and ccEe phenotypes presented intermediate values that did not differ significantly. The analysis of erythrocytes carrying the C antigen (n=26) showed a value of 13605,0 ± 12196,0. It was significantly lower than the value found in samples without this antigen (n=8) 19088,5 ± 15290,0, (p<0,05, Mann-Whitney test). On the other hand, no significant differences were found due to the presence of the E antigen. The results obtained suggest that the C antigen has a negative effect on the RhD protein expression. Considering that the Rh polypeptides require the RhAG glycoprotein association for their membrane integration and the high homology between RhCe and RhD, the decrease in the D antigen expression found in samples carrying the C antigen may be the result of a privileged affinity of the RhCe variant for RhAG, placing the RhD protein in a detrimental position.