Asian Journal of Transfusion Science
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CASE REPORT Table of Contents   
Year : 2015  |  Volume : 9  |  Issue : 1  |  Page : 92-93
Anti-N antibody reacting at 37°C: An unusual occurrence interfering with routine testing: Two interesting cases


1 Department of Transfusion Medicine, Citizens Hospital, Nallagandla, Serilingampally, Hyderabad, India
2 Department of Transfusion Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India

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Date of Web Publication6-Feb-2015
 

   Abstract 

Most anti-N antibodies are naturally occurring, IgM antibodies, and not active above 25°C and are not clinically significant but IgG anti- N has also been described. Immune anti-N resulting from multiple transfusions does occur & has been implicated as the cause of hemolytic transfusion reactions and mild hemolytic disease of fetus and newborn. Anti- N reacting at room temperature can be a cause for ABO blood group discrepancy

Keywords: Anti-N antibody, naturally occurring anti-N, warm reacting antibody

How to cite this article:
Kumawat V, Jain A, Marwaha N, Sharma RR. Anti-N antibody reacting at 37°C: An unusual occurrence interfering with routine testing: Two interesting cases. Asian J Transfus Sci 2015;9:92-3

How to cite this URL:
Kumawat V, Jain A, Marwaha N, Sharma RR. Anti-N antibody reacting at 37°C: An unusual occurrence interfering with routine testing: Two interesting cases. Asian J Transfus Sci [serial online] 2015 [cited 2019 Oct 22];9:92-3. Available from: http://www.ajts.org/text.asp?2015/9/1/92/150964



   Introduction Top


MNS blood group system was the second to be discovered by Landsteiner and Levine in 1927 after ABO blood group system. Among antibodies of MNS blood group system, anti-M is a relatively common "naturally occurring" antibody. [1] Anti-N is relatively rare compared with anti-M; [1],[2] in one series of 86,000 patients, only two examples of anti-N were found (Croucher, personal communication). [3] It is very rare for anti-N to be formed as an immune antibody, [3] only two such cases have been reported in literature [3] by Callender and Race [4] and Ballas et al.[5] Perrault found only eight cases of anti-N in 45,000 blood samples against M− N+ (or M+ N+) cells in the auto analyzer, using a low ionic-strength polybrene method. [1] Most anti-N antibodies are naturally occurring IgM antibodies. These are usually not active above 25° C and not considered clinically significant. [6] The anti- N of IgG type has also been described in literature. [1] Immune anti-N resulting from multiple transfusions do occur, usually in people of African origin with M+ N− S− s− U− red cells. [5] Anti-N has been implicated as the cause of hemolytic transfusion reactions (HTRs) [5] and mild hemolytic disease of the fetus and newborn also. [7] Here, we report two cases (one donor and one patient) of naturally occurring anti-N reacting at 37°C.


   Case Reports Top


Case 1

A 60-year-old patient was admitted in neurosurgery ward of our institute to be operated for parietal space occupying lesion with no history of previous transfusion. Blood sample received for four units of packed red cells using conventional tube technique showed preliminary blood group as A Rh D positive, but in the reverse grouping the patient's serum was reacting with all the three pooled A, B and O reagent red cells (4+ agglutination in tube) with negative autocontrol. Three cell screening panel (Diacell, Biorad, 1785, Cressier s/Morat, Switzerland) and 11 cell identification panel using conventional tube technique (Diapanel, Biorad, 1785, Cressier s/Morat, Switzerland) showed the presence of anti-N specificity. Antibody was reacting with similar maximum strength of reaction (4+) after 1 h water bath incubation at 37°C. Dithiothreitol (DTT) treatment of serum showed IgM type of immunoglobulin. Enzyme treatment of red cell could not be performed on patient sample. The anti-N titer was 1:32 at room temperature (doubling dilution). Patient's MNS phenotype was M+ N− S− s+. The red cells which were N− were compatible with patient serum both in the saline phase and the AHG phase. Reverse grouping with N− pooled ABO reagent red cells also resolved patient's blood group discrepancy.

Case 2

The blood group of a 24-year-old female repeat whole blood donor who donated for 5th time was reported as blood group discrepancy as her serum was reacting with pooled reagent O cells. Preliminary blood group of donor using conventional tube technique was O Rh D positive but in the reverse grouping there was a reaction with all three reagent red cells with autocontrol negative. Anti-H lectin with donor red cell was 4+ using conventional tube technique. Three cell screening panel (Diacell, Biorad, 1785, Cressier s/Morat, Switzerland) and 11 cell identification panel (Diapanel, Biorad, 1785, Cressier s/Morat, Switzerland) showed the presence of anti-N specificity using conventional tube technique. The antibody was reactive at room temperature and also at 37°C. DTT treatment of serum showed IgM type of immunoglobulin. Donor's MNS phenotype was M+ N− S− s+. Reverse grouping with N− pooled ABO reagent red cell resolved the patient's the blood group discrepancy. The previous blood grouping results were not traceable, but there was no history of blood transfusion and pregnancy in blood donor, so antibody can be considered as naturally occurring.


   Discussion Top


Anti-N is usually not active at 37°C. It can generally be ignored in transfusion practice and if the room temperature incubation is eliminated from compatibility testing and screening for antibodies, antibody will usually not be detected. [8] The anti-N antibody in both of our cases was IgM type, having a wide thermal amplitude reacting at 37°C and capable of causing HTR. ABO discrepancy due to cold alloantibodies (e.g., anti-M) or autoantibodies (e.g., anti-I) reacting with reverse grouping cells, leading to unexpected positive reactions have been described in the literature. [9] In both the cases, anti-N was detected at an earlier stage as interfering with reverse grouping.

 
   References Top

1.
Perrault R. Naturally-occurring anti-M and anti-N with special case: IgM anti-N in a NN donor. Vox Sang 1973;24:134-49.  Back to cited text no. 1
[PUBMED]    
2.
Race RR, Sanger R. Blood Groups in Man. 6 th ed. Oxford: Blackwell Scientific Publications; 1975.  Back to cited text no. 2
    
3.
Other red cell antigens. In: Klein HG, Anstee DJ, editors. Mollison's Blood Transfusion in Clinical Medicine. 11 th ed. Malden, Massachusetts, USA: Blackwell Publishing Ltd.; 2005. p. 221.  Back to cited text no. 3
    
4.
Callender ST, Race RR. A serological and genetical study of multiple antibodies formed in response to blood transfusion by a patient with lupus erythematosus diffusus. Ann Eugen 1946;13:102-17.  Back to cited text no. 4
[PUBMED]    
5.
Ballas SK, Dignam C, Harris M, Marcolina MJ. A clinically significant anti-N in a patient whose red cells were negative for N and U antigens. Transfusion 1985;25:377-80.  Back to cited text no. 5
[PUBMED]    
6.
Mollison PL, Engelfriet CP, Contreras M. Blood Transfusion in Clinical Medicine. 10 th ed. Oxford: Blackwell Science; 1997.  Back to cited text no. 6
    
7.
Telischi M, Behzad O, Issitt PD, Pavone BG. Hemolytic disease of the newborn due to anti-N. Vox Sang 1976;31:109-16.  Back to cited text no. 7
[PUBMED]    
8.
Daniels G. Other blood groups. In: Roback JD, Grossman BJ, Harris T, Hillyer CD, editors. Technical Manual. 17 th ed. Bethesda, Maryland, USA: American Association of Blood Bank; 2011. p. 416.  Back to cited text no. 8
    
9.
Cooling L. ABO, H, and Lewis blood groups and structurally related antigens. In: Roback JD, Grossman BJ, Harris T, Hillyer CD, editors. Technical Manual. 17 th ed. Bethesda, Maryland, USA: American Association of Blood Bank; 2011. p. 272.  Back to cited text no. 9
    

Top
Correspondence Address:
Ashish Jain
Department of Transfusion Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-6247.150964

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