Détermination du groupe ABO: Bilan de cinq ans d'utilisation quotidienne et évaluation sur des échantillons sélectionnés

Abstract

Summary 1) Five years of routine use . More than four million routine runs on Groupamatic including ABO group determination have been processed in our routine work conditions. Thus different genotype and phenotype frequencies were reconfirmed : − on 108.509 donors ( 1976 ) : · O 42.48 ‰ · A 44.10 ‰ · B 9.56 ‰ · AB 3.86 ‰ − on 150.000 tests processed continuously ( 1973 ) : · A 3 0.060 ‰ · A x 0.013 ‰ · A end or A y 0.007 ‰ · A el 0 · A 3 B 0.433 ‰ · A weak 0.260 ‰ − on 37.460 donors ( 1975 ) : · A 11 0.2142 · A 2 0.0609 · B 0.0666 · O 0.6583 · A 2 B ( calculated ) 0,008027 · A 2 B ( observed ) 0,007784 This determination was checked by numerous comparisons between our results and those obtained manually existing previously in donor files. Several problems can be discussed, particularly : -- a large excess of A3B phenotypes was observed and confirmed manually on opaline plate. It shows that the interaction depression effects in the heterozygote are common in the ABO group system. It seems that the low frequency of detection observed until now was due to the generalized utilisation of centrifugation for grouping, -- artificial or natural chimeras were studied : only the A/O and B/O one comprising 80 % of A or B and more are not detected : all the AB chimeras are refused, even at the extreme percentages, -- the Bombay phenotypes studies routinely were all rejected, -- the problem of O phenotypes without anti-A antibodies appeared to be more frequent than expected. 2) Evaluation on selected specimens : weak A, weak B and cis AB . These 53 specimens were recently tested blindly on 360 and MG50 equipments, in routine and using reagents of medium capacity without any quantitative detection purpose : -- no quantitative measurements were made, and percentages inferior to 20 as Aend or superior to 80 as some cis AB could not be detected, -- the equilibrium status of the reaction was not reached so low kinetic reactions for e.g. some Bx agglutinations gave results inferior to those observed when in equilibrium phase. In spite of this handicap, in routine, most of these samples were refused, particularly as concerns the ABO logic interpretation. The results obtained date as follows : -- 11 A3 samples : all refused ; -- 8 Ax samples : all refused ; -- 8 Aend samples : all refused ; -- 2 Am samples : all refused ; -- 4 Ael samples : only one is rejected, the 3 others looking like O group, the results being the same in manual techniques, -- 6 B3 samples among which 1 A1B3 : all refused, -- 5 Bx samples among which 2 A1Bx : all refused, -- 9 cis AB samples : all refused. In conclusion, the 360 or MG 50 Groupamatic equipments are able to detect rare ABO phenotypes with performances at least equal to those of the most accurate manual techniques.