B Subgroup : Bx blood Group in a Patient : A Case Report

This is a report of a case of B Sub Group: Bx, first ever detected in Bangladesh, while doing compatibility test of a sample of a patient undergoing cardiac surgery. The patient was referred to the transfusion medicine department of Bangabandhu Sheikh Mujib Medical University to do cross-match with 8 proposed donors of same ABO group prior to cardiac surgery. His red cells showed weak agglutination with anti-B, anti-AB and in his serum there was potent Anti-A and weak anti-B which was not detected at 370C. After adsorption with anti-B an elute was prepared from patient’s cells which agglutinate with B and AB cells but did not agglutinate with A or O cells. The patient could be transfused with B blood but in this situation of cardiac surgery, as he should have to be kept in hypothermic condition, we transfused him with O washed red cell with AB plasma during operation. Patient was released from hospital without any complication. The weak B subgroups are: B3, Bx & Bel. B3 shows a mixed field of agglutination with anti B. Bx shows a weak agglutination and weak anti-B is found in the serum. Bel is not agglutinated with anti-B but is only adsorbed anti-B. With meticulous attention, cell & serum grouping of recipient and proposed donor/s to be done along with 3 phase cross-matching (Saline phase at room temp, at 4 and 37 degree Celsius temp, Indirect Coomb’s Test phase) to ensure right blood to the right patient at right time.

proposed that the weak B should be used as follows: B 3 , B x & B el .B 3 shows a mixed field of agglutination with anti B. B x shows a weak agglutination and weak anti-B is found in the serum and his saliva inhibits the reaction between anti-B and B cells.B el are not agglutinated with anti-B only adsorbed anti-B. 2,3 the routine determination of ABO blood groups, anti-A, anti-B and anti-AB are used for testing red cells for A and B antigens.The group is checked in serum or reverse grouping by testing the serum against known A, B & O red cells.We are reporting a case of B subgroup: Bx first ever detected in Bangladesh.

Case Report:
A 46-year-old man was admitted in the cardiac surgery ward of Bangabandhu Sheikh Mujib Medical University (BSMMU) for surgical repair of Aortic valvular disease.Before operation, his blood group was identified as O +ve (positive).On the day before operation, 8 donors of O +ve (positive) came with patient's sample for cross-matching, screening etc.During cross matching, his sample was found incompatible with all the donors.Then we gave special attention in doing his ABO grouping.
During cross-matching with B+ve and B-ve donors, we could detect that the sample had major incompatibility at room temperature and 4 0 C but not at 37 0 C. His saliva inhibited the reaction of anti-B with B cells.So we then realized that his blood group was B x that contains weak anti-B too.After adsorption with anti-B an elute was prepared from patient's cells which agglutinated with B and AB cells but did not agglutinate with A or O cells.
Elutes agglutinated with B and AB red cells did not agglutinate with A or O cells.B substance was present in his saliva, which inhibited the reaction between anti-B and B cells.We then advised to transfuse the patient with O washed red cell with AB plasma.All seven siblings' of the patient had blood group B+ve, the parents' blood groups could not be explored.Subgroups are characterized by decreasing numbers of antigen sites on the red cells and the reciprocal increase in H antigen activity. 5,6Subgroups are more often recognized when there is a discrepancy between the red cells and serum grouping.Most of the laboratories are doing blood groups only by forward grouping; these results are not checked by doing Reverse grouping.Moreover, they perform grouping in slide method in which weak antigens are not detected and as a result the persons are typed wrongly.

Conclusions:
Usually subgroups are wrongly typed as O, which may cause HTR (Hemolytic Transfusion reaction), leading to death. 8, 9, 10B 3 shows a mixed field of agglutination with anti B. B x shows a weak agglutination and weak anti-B is found in the serum.B el cells are not agglutinated with anti-B only absorbed anti-B. 11,12 iculous attention to cell & serum grouping of recipient and proposed donor/s to be done along with 3 phase cross-matching (Saline phase at room temp, 4 and 37 degree Celsius temp, ICT phase) to ensure right blood to the right patient at right time.

Table - II
Antigens and antibodies present in B blood group

Table - I
Antibodies and antigens found in patient's sample NB: Table-I revealed in forward grouping -B group and reverse grouping -O group) (