|Year : 2020 | Volume
| Issue : 2 | Page : 228-229
A case of naturally occurring anti-E mimicking anti-A1
Vinu Rajendran1, Revathy Nair2, AP Poornima3, Debasish Gupta4
1 Department of Immunohematology and Blood Transfusion, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Karnataka, India
2 Department of Transfusion Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
3 Department of Transfusion Medicine, Government Medical College, Kollam, Kerala, India
4 Department of Transfusion Medicine, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
|Date of Submission||23-Mar-2020|
|Date of Decision||07-Aug-2020|
|Date of Acceptance||14-Sep-2020|
|Date of Web Publication||13-Nov-2020|
Department of Immunohematology and Blood Transfusion, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Karnataka
Source of Support: None, Conflict of Interest: None
Rhesus (Rh) antibodies are usually of the acquired IgG type. Naturally occurring IgM type of Rh antibody is unusual. We report a case of naturally occurring IgM anti-E which mimicked anti-A1. ABO grouping of a 61-year-old man posted for surgery showed discrepancy. Cell group corresponded to A positive while reverse grouping showed weak agglutination with A cells. Nonreactivity of red cells with A1 lectin suggested the possibility of A subgroup with anti-A1. Anti-A1 was ruled out on further testing of serum with A1-positive red cells. Antibody screening and identification revealed the presence of anti-E. The presence of Rh E antigen in the reagent A cell was the reason for weak agglutination. Antibody titer of 4 and 2 was observed at 4°C and 37°C incubation, respectively, in the untreated serum. Antibody was undetectable in the dithiothreitol-treated serum both at 4°C and 37°C confirming the IgM nature of the antibody.
Keywords: Anti-E, IgM anti-E, IgM rhesus antibodies, naturally occurring anti-E, rhesus antibodies
|How to cite this article:|
Rajendran V, Nair R, Poornima A P, Gupta D. A case of naturally occurring anti-E mimicking anti-A1. Glob J Transfus Med 2020;5:228-9
| Introduction|| |
Rhesus (Rh) antibodies are usually acquired and are of IgG type. Only a few cases of naturally occurring IgM type Rh antibody are reported in the literature., Anti-E is an Rh antibody that has been implicated in hemolytic disease of the newborn (HDN) and delayed hemolytic transfusion reactions (DHTRs) though not usually severe. Yousuf et al. and Rasmussen et al. reported cases of naturally occurring anti-E antibody in the serum., We report a case of naturally occurring anti-E which apparently seemed like a case of subgroup of A blood group with anti-A1.
| Case Report|| |
Blood samples of a 61-year-old man with no history of transfusion admitted for cardiopulmonary bypass surgery were sent to our blood center for ABO grouping and Rh typing. Forward grouping corresponded to A Rh (D) positive. On reverse grouping, weak agglutination was obtained with A pooled cells. Auto-control (AC) was negative. There was no reaction with O pooled cells (blood grouping done by conventional test tube [CTT] method using commercial anti-sera and in-house prepared pooled A, B, and O cells).
To rule out anti-A1 as a possible cause of discrepancy, red cells were tested with A1-lectin and no agglutination was observed (CTT method using commercially available anti-A1). Hence, the primary impression was subgroup of A with anti-A1. The patient's serum was tested with two individual A1 cells to ensure the specificity of the antibody. A2 red cells were not available. Agglutination (2+) was obtained with one of the A1 cells (CTT method using in-house A1 cells). No consistent reaction was observed with A1 cells. Hence, the possibility of anti-A1 was ruled out. Antibody screening and identification at anti-human globulin phase revealed the presence of anti-E (column agglutination technology using commercial 3-cell and 11-cell panel). The patient was further phenotyped as R1R1 (Rh E negative) (CTT method using commercial anti-E) and thus confirmed the presence of anti-E.
Rh phenotyping of A1 cells showed that cells which reacted with the patient's serum had E antigen while the cells which did not react were E antigen negative (CTT method using commercial antisera). This explained the variable reactivity of the serum with the A1 cells. One of the donor units used to prepare pooled A cells had E antigen which explained the reactivity of serum with pooled A cells.
Serum was treated with 0.01 Molar dithiothreitol (DTT) and titrated in parallel with untreated serum (CTT method). In-house O + cells of RzRz phenotype were used for titration since R1R2 and R2R2 were not available. A titer of 4 and 2 was observed at 4°C and 37°C incubation, respectively, in the untreated serum. Antibody was undetectable in the DTT-treated serum both at 4°C and 37°C. This suggested the presence of IgM type of antibody which explained the saline phase reactivity. Two E-negative, A + packed red cell units were selected from the inventory and were found compatible.
| Discussion|| |
Initially, the discrepancy was mimicking a case of subgroup of A with anti-A1. Immunohematology workup revealed it as a case of naturally occurring anti-E. Considering the reactivity with E antigen-positive “A” cells at saline phase and disappearance upon treatment with DTT, it was most likely to be an IgM antibody. Persistence of the reaction pattern in antibody screening at 37°C suggests a wide thermal amplitude of reactivity. There is an increase in incidence of detection of anti-E due to antibody screening and usage of enzyme techniques in immunohematology. Naturally occurring anti-E is a rare entity. Šimc and Rožman reported a rare case of naturally occurring anti-E in a 3-month-old infant. Furthermore, Harrison suggested that most of the anti-E, especially the papain reactive, are initially due to natural stimuli and are further stimulated by transfusion and pregnancy. Dybkjaer suggested the possibility of recent immunization like poliomyelitis vaccination as a stimulus for the production for anti-E. Naturally occurring anti-E is usually not clinically significant. No case of HDN or DHTR associated with naturally occurring anti-E has been reported. Even though naturally occurring anti-E is not considered clinically significant, corresponding antigen-negative packed red cell is preferred for transfusion. Finding an E antigen-negative red cell unit is not difficult as the frequency of E antigen is only 20% in the Indian population. Proper documentation of the presence of antibody shall be ensured to prevent further delay in issue of compatible blood in the future.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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