If the antibody screen is positive, the specificity of the antibody is identified by testing the serum against a panel of 8 to 20 Group O RBCs of varying phenotypes. The pattern of positive and negative reactions with these cells identifies the antigen against which the antibody is directed. Antibody identification is accomplished by the “crossing out” method which consists of identifying each cell that is negative and crossing
out all of the antigens present on that cell. The panel should also be observed to: From this information, one can determine:
Thermal characteristic Pattern of Reactivity Autocontrol Interpretation Stronger at cold & weaker at warm temperature One or few cells positive Negative Consider cold alloantibody such as MN, P, Le, etc. Stronger at cold & weaker at warm temperature All cells positive Negative Consider Vel, Tja, etc. Stronger at cold & weaker at warm temperature All cells posiitve Positive Cold autoantibody such as anti-I Negative in cold & positive at warmer temperature One or few cells positive Negative Consider clinically significant alloantibody such as Rh, Kell, Duffy, Kidd, Ss, etc Negative in cold & positive at warmer temperature All cells positive Negative Consider alloantibody to high frequency antigen KPb, k, Lub, Jsb, Lan, Ge, Ata, U, etc Negative in cold & positive at warmer temperature All cells positive Positive Consider autoantibody with or without alloantibody If a clinically significant antibody is identified, only red cells negative for the relevant antigen will be selected for crossmatching and transfusion. For example, if the antibody is anti-K, RBC of the appropriate ABO and Rh type will be tested with anti-K anti-serum and only K-negative red cells will be selected for transfusion. For added safety, an AHG crossmatch is also performed. For clinically insignificant antibodies, it is permissable to crossmatch units that have not been antigen typed. When the antibody screen is positive, additional time is required to identify the antibody(ies), to find antigen-negative red cells, and to perform AHG crossmatches. This time can range from an hour to days if multiple antibodies, antibodies against high frequency antigens, or a mixture of autoantiobody and alloantibodies are present. If transfusion is medically necessary before compatible blood can be obtained, the attending physician and the transfusion medicine physician need to discuss the risk:benefit ratio of transfusing potentially incompatible blood. An autoantibody is produced against a person’s own red cells. When a patient has an autoantibody, the direct antiglobulin test and the autocontrol in an antibody panel will be positive. In addition, all cells in the panel will be reactive. If the antibody reactions are stronger at colder temperatures and weaker at warm temperatures, the patient probably has a cold autoantibody. If the antibody reactions are negative at colder temperatures and positive at warmer temperatures, the patient most likely has a warm autoantibody.  Ann Lab Med. 2016 May; 36(3): 284–286. Young Eun Koh, M.D., Geun Young Ryu, M.D., Yoon-ho Kim, M.T., Mi-Ae Jang, M.D., Soo-young Yoon, M.D.,
and Chae Seung Lim, M.D. Dear Editor, Anti-H antibody is a type of anti-red blood cell (RBC) antibody that agglutinates with H antigen, which is universally present on human RBCs. The most widely known problem related to the anti-H antibody is the potentially lethal hemolytic transfusion reaction seen in individuals with the Bombay O blood type [1,2,3]. Other anti-H antibodies are mostly found in A1 or A1B blood type individuals and are usually cold reactive and clinically benign [3]. We report a Korean patient with an anti-H antibody exhibiting a wide thermal range. A 79-yr-old woman diagnosed with pneumonia was due to receive a transfusion of RBCs in the Guro hospital of Korea University, Seoul, Korea. Her blood type was A, RhD+. However, the antibody-screening test was positive; an antibody identification test revealed 11 positive panels with no reaction to autologous RBCs by using the Ortho BioVue Innova system (Ortho-Clinical Diagnostics, Raritan, NJ, USA). The manufacturer's test RBCs used in the antibody screening and identification tests were O cells. ABO serotyping of the patient's serum with O cells showed strong agglutination. We suspected anti-IH or anti-H antibodies with wide thermal amplitude and conducted further evaluation [4]. An ABO genotyping was performed for accurate genotype identification. Various types of RBCs from random donors were used, including autologous A1, adult O, RhD- O, A1, and enzyme-treated O cells. A1 cells were tested with the patient's serum using both the column agglutination test (CAT) and tube method [5,6]. Cord blood A1, B, O, and A1B cells were tested to rule out the possibility of anti-IH antibodies [7]. Additionally, dithiothreitol (DTT)-treated serum was tested with O cells to specify the antibody's immunoglobulin type. The Ortho BioVue Innova system was used for the CAT; tests were carried out at room temperature and Coombs' phase where appropriate. All tests were conducted according to the procedures indicated in the AABB Technical Manual and with methods described by the relevant manufacturers [3]. The patient was identified as having an A102/A102 genotype through sequence analysis. The antibody identification test showed 4+ in all panels through saline, 30 min cold incubation, albumin, and Coombs' phase; no agglutination with autologous RBCs was observed as noted above. The CAT of the patient's serum with adult A1 cells showed no agglutination, including autologous RBCs. Tests with adult O cells revealed agglutination of 3+ or more in all phases. These results suggested the presence of anti-IH or anti-H antibodies, as did the strong reaction with H antigen-abundant O cells and weak or absent reactions with A1 cells that lacked H antigens. Enzyme treatment of RBCs did not cause any significant changes in reactivity to O cells, while papain-treated A1 cells showed agglutination of 2+ or more. The specific effect of enzyme treatment on A1 cells in reaction with anti-H or anti-IH antibodies was unclear; results of this test did not favor any specific type of antibody (Table 1). Table 1Column agglutination test with various RBCs
Cord blood A1 cells showed weak reactions only in the tube method performed at room temperature. Neonatal RBCs have incomplete development of ABO antigens and have fewer H antigens on their surface compared with adult RBCs [3]. Thus, these results suggested that the antibody reacted with a small amount of H antigen left on RBCs with an incomplete A1 phenotype. Cord blood O cells showed 3+ reactions only at room temperature. The lack of agglutination in Coombs' phase was interpreted as a weakened reaction due to fewer H antigens on RBC surfaces. DTT-treated serum showed no agglutination with adult O cells in contrast to phosphate-buffered saline (PBS)-mixed control samples, as the treatment inactivated IgM, which were identified as cold antibodies with a sufficiently high titer to react in the Coombs' phase (Table 2). Table 2Adult O cell with dithiothreitol-treated serum
Anti-IH antibody reacts weakly or not at all with I-RBCs, and reacts strongly only in the presence of both I and H antigens [7,8]. Cord blood RBCs lack I antigens; therefore, 3+ agglutination of cord blood O cells at room temperature signified the presence of anti-H antibodies. Adult Oi cells could have further confirmed this diagnosis; however, blood of that type was unavailable. The patient received a transfusion shortly after the identification test, and further evaluations at 4℃ could not be performed owing to insufficient sample amount. In conclusion, we identified a case of anti-H antibody with a high titer, which was not reported in previous studies of the frequencies of unexpected antibodies in the Korean population [9,10]. This report contributes to identification of anti-H antibodies in cases of unusual ABO discrepancies. FootnotesAuthors' Disclosures of Potential Conflicts of Interest: No potential conflicts of interest relevant to this article were reported. References1. Davey RJ, Tourault MA, Holland PV. The clinical significance of anti-H in an individual with the Oh (Bombay) phenotype. Transfusion. 1978;18:738–742. [PubMed] [Google Scholar] 2. Le Pendu J, Lambert F, Gérard G, Vitrac D, Mollicone R, Oriol R. On the specificity of human anti-H antibodies. Vox Sang. 1986;50:223–226. [PubMed] [Google Scholar] 3. Fung MK, Grossman BJ, et al., editors. Technical manual. 18th ed. Bethesda: American Association of Blood Banks; 201. [Google Scholar] 4. Waldner M, Rossetti G, Boccagni P, Ripamonti M. A report of an anti-H antibody with a wide thermal range in a group A(1) blood donor. Blood Transfus. 2007;5:41–43. [PMC free article] [PubMed] [Google Scholar] 5. South SF. Antibody screening and direct antiglobulin testing using BioVue column agglutination technology versus standard tube tests. Immunohematology. 1993;9:78–80. [PubMed] [Google Scholar] 6. Lapierre Y, Rigal D, Adam J, Josef D, Meyer F, Greber S, et al. The gel test: a new way to detect red cell antigen-antibody reactions. Transfusion. 1990;30:109–113. [PubMed] [Google Scholar] 7. Irani MS. Hemolytic transfusion reaction due to anti-IH. Transfusion. 2011;51:2676–2678. [PubMed] [Google Scholar] 8. Harvey GK, David JA, et al., editors. Mollison's blood transfusion in clinical medicine. 12th ed. Oxford: Wiley Blackwell; 2014. [Google Scholar] 9. Park BM, Song YK, Kim TS, Lee GH, Choi JS, Seong MW, et al. The frequency and distribution of unexpected red cell antibodies at National Cancer Center. Korean J Blood Transfus. 2009;20:120–128. [Google Scholar] 10. Kim SY, Kang JE, Song DY, Kim KH, Kim HH, Lee EY, et al. Comparison of the frequencies and distributions of unexpected antibodies based on different calculation criteria. Korean J Lab Med. 2009;29:152–157. [PubMed] [Google Scholar] Articles from Annals of Laboratory Medicine are provided here courtesy of Korean Society for Laboratory Medicine Which group of antibodies generally reacts most strongly at room temperature or colder temps quizlet?Anti-H reacts most strongly at room temperature with group O screening cells and weaker or negative at room temperature with autologous or donor group A1 cells.
What are the antibodies that react at room temperature and are considered clinically significant?[1] Some examples of anti-M antibody, however, are known to be clinically significant in nature as they are reactive at 37°C and have been known to cause HDFN[2,3] and HTRs.
What temperature do IgM antibodies react?Saline tests detect IgM antibodies and can be done at 4°C, 15°C, RT, or 37°C, In general, IgM antibodies react best at 4°C. Some have a maximum range of RT (22°C), and a few can react at 37°C (body temperature) and be clinically significant.
What are the cold reacting antibodies?Cold agglutinins – Cold agglutinins are antibodies that recognize antigens on red blood cells (RBCs) at temperatures below normal core body temperature. They can cause agglutination of the RBCs (picture 1) and extravascular hemolysis, resulting in anemia, typically without hemoglobinuria.
|
