Blood compatibility testing: Difference between revisions
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==Blood typing== | ==Blood typing== | ||
[[File:ABO blood type.svg|thumb| | [[File:ABO blood type.svg|thumb|450px|ABO antigens and antibodies]] | ||
Upon direct testing by adding antibodies against A, B and/or Rh to patient blood, agglutination means that the patient has the antigen tested. Upon indirect testing by adding A or B antigen to patient plasma, agglutination means ''absence'' of the antigen in the patient (and thus the patient produces antibodies against it). | Upon direct testing by adding antibodies against A, B and/or Rh to patient blood, agglutination means that the patient has the antigen tested. Upon indirect testing by adding A or B antigen to patient plasma, agglutination means ''absence'' of the antigen in the patient (and thus the patient produces antibodies against it). | ||
=== | ===Identification of non-ABO antibodies=== | ||
In the antibody screening procedure, an individual's plasma is added to a panel of two or three sets of red blood cells which have been chosen to express most clinically significant blood group antigens. Agglutination of the screening cells by the plasma, with or without the addition of anti-human globulin, indicates that an unexpected blood group antibody is present. If this occurs, further testing using more cells (usually 10–11) is necessary to identify the antibody. By examining the antigen profiles of the red blood cells the person's plasma reacts with, it is possible to determine the antibody's identity | In the antibody screening procedure, an individual's plasma is added to a panel of two or three sets of red blood cells which have been chosen to express most clinically significant blood group antigens. Agglutination of the screening cells by the plasma, with or without the addition of anti-human globulin, indicates that an unexpected blood group antibody is present. If this occurs, further testing using more cells (usually 10–11) is necessary to identify the antibody. By examining the antigen profiles of the red blood cells the person's plasma reacts with, it is possible to determine the antibody's identity as follows: | ||
<gallery mode=packed heights=500px> | |||
File:Serology interpretation of antibody panel for blood group antigens.jpg | |||
</gallery> | |||
The image above shows the interpretation of an antibody panel used to detect antibodies towards the most relevant blood group antigens. Each row represents "reference" or "control" red blood cells of donors which have known antigen compositions and are ABO group O. A + means that the antigen is present on the reference red blood cells, and 0 means it is absent; nt means "not tested". The "result" column to the right displays reactivity when mixing reference red blood cells with plasma from the patient in 3 different phases: room temperature, 37°C and AHG (with anti-human globulin, by the indirect antiglobulin test).<ref name=UtahU>{{cite web|url=https://arup.utah.edu/media/AntibodyIdentification/Introduction%20to%20Antibody%20Identification.pdf|title=Introduction to Antibody Identification|author=Justin R. Rhees, M.S., MLS(ASCP)CM, SBBCM|website=University of Utah, Medical Laboratory Sciences|access-date=2020-12-18}}</ref> | The image above shows the interpretation of an antibody panel used to detect antibodies towards the most relevant blood group antigens. Each row represents "reference" or "control" red blood cells of donors which have known antigen compositions and are ABO group O. A + means that the antigen is present on the reference red blood cells, and 0 means it is absent; nt means "not tested". The "result" column to the right displays reactivity when mixing reference red blood cells with plasma from the patient in 3 different phases: room temperature, 37°C and AHG (with anti-human globulin, by the indirect antiglobulin test).<ref name=UtahU>{{cite web|url=https://arup.utah.edu/media/AntibodyIdentification/Introduction%20to%20Antibody%20Identification.pdf|title=Introduction to Antibody Identification|author=Justin R. Rhees, M.S., MLS(ASCP)CM, SBBCM|website=University of Utah, Medical Laboratory Sciences|access-date=2020-12-18}}</ref> | ||
* '''Step 1'''; Annotated in blue: starting to exclude antigens without reaction in all 3 phases; looking at the first reference cell row with no reaction (0 in column at right, in this case cell donor 2), and excluding (here marked by X) each present antigen where the other pair is either practically non-existent (such as for D) or 0 (presence is homozygous, in this case homozygous c).<br>When both pairs are + (heterozygous cases), they are both excluded (here marked by X), except for C/c, E/e, Duffy, Kidd and MNS antigens (where antibodies of the patient may still react towards blood cells with homozygous antigen expression, because homozygous expression results in a higher dosage of the antigen).<ref name= | * '''Step 1'''; Annotated in blue: starting to exclude antigens without reaction in all 3 phases; looking at the first reference cell row with no reaction (0 in column at right, in this case cell donor 2), and excluding (here marked by X) each present antigen where the other pair is either practically non-existent (such as for D) or 0 (presence is homozygous, in this case homozygous c).<br>When both pairs are + (heterozygous cases), they are both excluded (here marked by X), except for C/c, E/e, Duffy, Kidd and MNS antigens (where antibodies of the patient may still react towards blood cells with homozygous antigen expression, because homozygous expression results in a higher dosage of the antigen).<ref name=Mais2014>{{cite book | last=Mais | first=Daniel | title=Quick compendium of clinical pathology | publisher=American Society for Clinical Pathology Press | publication-place=United States | year=2014 | isbn=978-0-89189-615-9 | oclc=895712380 }}</ref> Thus, in this case, E/e is not excluded in this row, while K/k is, as well as Js<sup>b</sup> (regardless of what Js<sup>a</sup> would have shown).<ref group=note>Besides from C/c, E/e, Duffy, Kidd and MNS, clinically significant dosage effects is rare but not impossible for other antigens, which thus may still be considered if subsequent cross-matching is reactive.</ref> | ||
* '''Step 2''': Annotated in brown: Going to the next reference cell row with a negative reaction (in this case cell donor 4), and repeating for each antigen type that is not already excluded. | * '''Step 2''': Annotated in brown: Going to the next reference cell row with a negative reaction (in this case cell donor 4), and repeating for each antigen type that is not already excluded. | ||
* '''Step 3''': Annotated in purple. Repeating the same for each reference cell row with negative reaction. | * '''Step 3''': Annotated in purple. Repeating the same for each reference cell row with negative reaction. | ||
* '''Step 4''': Discounting antigens that were absent in all or almost all reactive cases (here marked with \). These are often antigens with low prevalence, and while there is a possibility of such antibodies being produced, they are generally not the type that is responsible for the reactivity at hand. | * '''Step 4''': Discounting antigens that were absent in all or almost all reactive cases (here marked with \). These are often antigens with low prevalence, and while there is a possibility of such antibodies being produced, they are generally not the type that is responsible for the reactivity at hand. | ||
* '''Step 5''': Comparing the remaining possible antigens for a most likely culprit (in this case Fy<sup>a</sup>), and selectively ruling out significant differential antigens, such as with the shown additional donor cell type that is known to not contain Fy<sup>a</sup> but contains C and Jk<sup>a</sup> | * '''Step 5''': Comparing the remaining possible antigens for a most likely culprit (in this case Fy<sup>a</sup>), and selectively ruling out significant differential antigens, such as with the shown additional donor cell type that is known to not contain Fy<sup>a</sup> but contains C and Jk<sup>a</sup>. | ||
In this case, the antibody panel shows that anti-Fy<sup>a</sup> antibodies are present. This indicates that donor blood typed to be negative for the Fy<sup>a</sup> antigen must be used. Still, if a subsequent cross-matching shows reactivity, additional testing should be done against previously discounted antigens (in this case potentially E, K, Kp<sup>a</sup> and/or Lu<sup>a</sup>).<ref name=UtahU/> | In this case, the antibody panel shows that anti-Fy<sup>a</sup> antibodies are present. This indicates that donor blood typed to be negative for the Fy<sup>a</sup> antigen must be used. Still, if a subsequent cross-matching shows reactivity, additional testing should be done against previously discounted antigens (in this case potentially E, K, Kp<sup>a</sup> and/or Lu<sup>a</sup>).<ref name=UtahU/> | ||
{|class=wikitable align=right | {|class=wikitable align=right | ||
|+ Hemagglutination inhibition<ref name= | |+ Hemagglutination inhibition<ref name=Mais2014/> | ||
! Neutralizing substance !! Antigen cancelled | ! Neutralizing substance !! Antigen cancelled | ||
|- | |- | ||
| Line 34: | Line 36: | ||
| Guinea pig urine || Sd<sup>a</sup> | | Guinea pig urine || Sd<sup>a</sup> | ||
|} | |} | ||
When multiple antibodies are present, or when an antibody is directed against a high-frequency antigen, the normal antibody panel procedure may not provide a conclusive identification. In these cases, ''hemagglutination inhibition'' can be used, wherein a ''neutralizing substance'' cancels out a specific antigen.<ref name= | [[File:Fictional depiction of erythrocyte antigen neutralizers.png|thumb|Hemagglutination inhibition substances sound like they came from a witch brew!]] | ||
When multiple antibodies are present, or when an antibody is directed against a high-frequency antigen, the normal antibody panel procedure may not provide a conclusive identification. In these cases, ''hemagglutination inhibition'' can be used, wherein a ''neutralizing substance'' cancels out a specific antigen.<ref name=Mais2014/> Alternatively, the plasma may be incubated with cells of known antigen profiles in order to remove a specific antibody (a process termed ''adsorption''); or the cells can be treated with enzymes such as ficain or papain which inhibit the reactivity of some blood group antibodies and enhance others (see table below). | |||
===Clinical implication=== | |||
The following is a simplified classification for the main anti-erythrocyte antibodies, using mneumonics for the main involved antigen groups: | |||
*'''Anti-A/B antibodies''': These will cause immediate hemolytic transfusion reaction if the red blood cells do not have compatible antigens, even if there is no previous exposure to the antigens. Therefore, blood transfusions must always be ABO compatible. | |||
*'''"Kickers"-class antibodies''': Antibodies against '''Ki'''dd, '''Ke'''ll, '''R'''h, '''S''' and Duffy group antigens. These have a significant risk of causing hemolytic transfusion reactions when present, and therefore, patients with kickers-class antibodies should receive blood that is negative for the antigen, except for very critical situations where there is no time to find compatible blood.<ref>{{cite journal|author=Pamela P. Goodell, Lynne Uhl, Monique Mohammed, Amy A. Powers|title=Risk of Hemolytic Transfusion Reactions Following Emergency-Release RBC Transfusion|journal=American Journal of Clinical Pathology|volume=134|issue=2|year=2010|doi=10.1309/AJCP9OFJN7FLTXDB}}</ref> Kickers-class antibodies generally need a previous exposure to the antigen to form, with transfusion reactions being possible upon subsequent transfusions.<ref name=Mais2014/> Some patients first test positive and later test negative for a kickers-class antibody, but such patients must still be transfused with antigen-negative blood regardless.<ref name="uptodate">{{cite web|title=Pretransfusion testing for red blood cell transfusion|last=Uhl|first=L|date=11 Jan 2021|work=UpToDate|url=https://www.uptodate.com/contents/pretransfusion-testing-for-red-blood-cell-transfusion|access-date=27 Jan 2021}}</ref> They are generally of the IgG subtype, and are generally most active at 37°C. They can potentially cross the placenta and cause hemolytic disease of the newborn. They generally show increased reactivity against homozygously expressed antigens compared to heterozygously expressed ones (as mentioned in ''Step 1'' above). | |||
*'''"Limply"-class antibodies''': Antibodies against '''L'''utheran, '''I'''i, '''M'''/N, '''P1''', '''L'''ewis group antigens. These almost never cause clinically significant transfusion reactions (but anti-Ii antibodies are usually the type that causes cold agglutinin disease,<ref name=":5">{{cite journal | vauthors = Michalak SS, Olewicz-Gawlik A, Rupa-Matysek J, Wolny-Rokicka E, Nowakowska E, Gil L | title = Autoimmune hemolytic anemia: current knowledge and perspectives | journal = Immunity & Ageing | volume = 17 | issue = 1 | pages = 38 | date = November 2020 | pmid = 33292368 | pmc = 7677104 | doi = 10.1186/s12979-020-00208-7 | doi-access = free }}</ref> a form of autoimmune hemolytic anemia).<ref name=Mais2014/> Hence, there is generally no need to find blood that is negative for the antigen for a limply-class positive patient. These antibodies are generally naturally occurring, that is, they don't require a previous exposure to the antigen to form. They are generally of the IgM class, and are generally not reactive at body temperature, but rather most active at room temperature and below.<ref name="pmid33358685">{{cite journal| author=Ferdowsi S, Mohammadi S, Ahmadnezhad M, Herfat F, Rezvani A, Eshghi P | display-authors=etal| title=Anti-M antibody and ABO blood grouping discrepancy: a report of three cases with review of literature. | journal=Hematol Transfus Cell Ther | year= 2022 | volume= 44 | issue= 2 | pages= 288-290 | pmid=33358685 | doi=10.1016/j.htct.2020.09.150 | pmc=9123591 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=33358685 }} </ref> They generally pose no significant risk of hemolytic disease of the newborn (as IgM class antibodies do not cross the placenta). | |||
Following is a comparison of clinically relevant characteristics of antibodies against the main human blood group systems:<ref name= | Following is a comparison of clinically relevant characteristics of antibodies against the main human blood group systems:<ref name=Mais2014>{{cite book | last=Mais | first=Daniel | title=Quick compendium of clinical pathology | publisher=American Society for Clinical Pathology Press | publication-place=United States | year=2014 | isbn=978-0-89189-615-9 | oclc=895712380 }}</ref> | ||
{|class="wikitable" | {|class="wikitable" | ||
! !! | ! !! ABO !! Rh !! Kell !! Duffy !! Kidd !! Lutheran !! MNS !! Lewis !! P !! Ii | ||
|- | |- | ||
! Most common in immediate hemolytic transfusion reactions | ! Most common in immediate hemolytic transfusion reactions | ||
| Line 51: | Line 55: | ||
| || E,D,C|| || || Jk<sup>a</sup>|| || || || || | | || E,D,C|| || || Jk<sup>a</sup>|| || || || || | ||
|- | |- | ||
! Most common in | ! Most common in hemolytic disease of the newborn | ||
| Yes|| D,C|| Yes|| || || || || || || | | Yes|| D,C|| Yes|| || || || || || || | ||
|- | |- | ||
| Line 66: | Line 70: | ||
| Yes|| || || || || Yes|| M,N|| Yes|| Yes|| Yes | | Yes|| || || || || Yes|| M,N|| Yes|| Yes|| Yes | ||
|- | |- | ||
! Enhanced by | ! Enhanced by ficain<ref name="HillHanna2017">{{cite journal|last1=Hill|first1=Ben C.|last2=Hanna|first2=Courtney A.|last3=Adamski|first3=Jill|last4=Pham|first4=Huy P.|last5=Marques|first5=Marisa B.|last6=Williams|first6=Lance A.|title=Ficin-Treated Red Cells Help Identify Clinically Significant Alloantibodies Masked as Reactions of Undetermined Specificity in Gel Microtubes|journal=Laboratory Medicine|volume=48|issue=1|year=2017|pages=24–28|issn=0007-5027|doi=10.1093/labmed/lmw062|pmid=28007780|doi-access=free}}</ref> and papain<ref name=CSTM>{{cite web|title=Questions and Answers on Proteolytic Enzymes Used in Blood Group Serology|url=https://www.transfusion.ca/Resources/CSTM-Blog/January-2018/Questions-and-Answers-on-Proteolytic-Enzymes-Used|website=Canadian Society for Transfusion Medicine|author=Eric Ching|access-date=2021-01-28}}</ref> | ||
| Yes|| Yes|| || || Yes|| || || Yes|| P1||Yes | | Yes|| Yes|| || || Yes|| || || Yes|| P1||Yes | ||
|- | |- | ||
! Destroyed by | ! Destroyed by ficain<ref name="HillHanna2017" /> and papain<ref name=CSTM/> | ||
| || || ||Fy<sup>a</sup>, Fy<sup>b</sup>|| | | || || ||Fy<sup>a</sup>, Fy<sup>b</sup>|| | ||
| Yes|| Yes|| || || | | Yes|| Yes|| || || | ||