Transcription
Okay, so good morning! We are now continuing with our blood banking review. This time, our topic will be blood group immunology.
Remember that we have two types of antibodies that might be encountered in the blood bank laboratory. Blood group antibodies can be IgG or IgM, but rarely they can also be IgA. However, IgA is a rare type of antibody. Oftentimes, the antibodies we encounter are IgM and IgG. In our discussions on immunology, we have covered the characteristics of IgG antibodies.
During the introductory topic on blood banking, we divided our blood group systems into two categories based on the nature of the antigen. We emphasized that blood group systems with carbohydrate antigens often have antibodies that are IgM in nature. Conversely, naturally occurring antibodies are also often IgM, but not always. Examples of these antibodies include Lewis antigen antibodies, the I system, the P1PK system, the globoside, and some M and S antibodies. Again, these are often IgM in nature because the antigens of these blood group systems are carbohydrates.
For immune-type antibodies, in order to produce these antibodies, you need to be exposed to the RBC antigen first. This exposure could be due to transfusion, pregnancy, or transplantation. Examples of these antibodies include Rh antibodies, Kell, Duffy, and some M and S antibodies. These are IgG antibodies.
As we proceed with the different blood group techniques, you will notice that naturally occurring antibodies usually react best at room temperature. This is why they are often detected during immediate spin in pre-transfusion testing. Immune-type antibodies, on the other hand, are clinically significant and typically react best at the AHG phase.
Now, remember that there are two types of immune responses. The first immune response occurs the first time you are exposed to a particular antigen. This immune response usually happens days to months after a transfusion event. The initial antibody produced is often IgM, followed by IgG production. Eventually, IgM will disappear, but IgG will persist indefinitely.
The secondary immune response occurs in previously immunized individuals. This is the second time they are exposed to the same antigen. The secondary immune response is also known as an amnestic response. This time, large quantities of IgG will be produced, often associated with delayed hemolytic and serologic transfusion reactions.
How do we know that there is an antigen-antibody interaction in blood banking? This is through the concept of agglutination. In blood banking, we deal with particulate antigens, specifically blood cells, which is why we term this as agglutination.
The first step in agglutination is sensitization, where antibodies start to attach to their respective antigens. This attachment utilizes hydrogen bonds, van der Waals interactions, and electrostatic charges. These interactions are non-covalent, meaning they can be reversed.
The second phase of the interaction is the formation of an agglutination lattice. This occurs when antibody molecules span the distance between two adjacent red cells to form this lattice. The ability of a particular antibody to form a lattice depends on its class. IgM is considered the most potent when it comes to agglutination reactions. IgM supports direct agglutination, allowing us to visualize the agglutination reaction even without adding anti-human globulin.
In contrast, IgG antibodies, which only have two binding sites, find it difficult to span the distance between two adjacent red cells. Therefore, they often depend on indirect agglutination. To demonstrate the presence of IgG antibodies, we need to show that the red cells are coated with immunoglobulin G.
Remember that, aside from agglutination, hemolysis can also indicate an antigen-antibody interaction. When an antibody attaches to a red cell, it will elicit complement activation. The product of complement activation is cellular lysis. However, sometimes complement activation does not proceed completely. For example, activation of C3 may result in the deposition of the C3 component on the surface of the red cell.
We also have a specific type of anti-human globulin that can detect the presence of complement proteins on the surface of the red cell, indicating complement activation due to the presence of an antibody.
Several factors affect agglutination. First is centrifugation speed and time. Our red cells naturally repel each other due to being surrounded by a negative charge, which creates a repulsive potential. Centrifugation brings the red cells closer together to potentiate the antigen-antibody reaction.
The concentration of antigen and antibody is also important. We must reach the zone of equivalence to visualize the reaction. The pH can affect the reaction as some antibodies react more strongly at lower pH levels, such as below 6.5.
Temperature and immunoglobulin class also play a role. IgM antibodies are usually detected during immediate spin because they react best at room temperature, while IgG antibodies typically react at 37 degrees Celsius.
Increasing incubation time can help demonstrate weak or absent reactions. We may also incubate at different temperatures to provide the right environment for the reaction. The use of enhancement media is especially important for detecting IgG antibodies, as it promotes antibody binding to the antigen.
We can use 22% albumin, low ionic strength solutions, polyethylene glycol, and human proteolytic enzymes. However, the use of proteolytic enzymes depends on the type of antibody reacting in the system. Some antibodies are enhanced by these enzymes, while others are destroyed or negated after enzyme treatment.
Now, let us proceed to the anti-globulin test technique. For the anti-human globulin test, or Coombs technique, we use an AHG reagent, which is an antibody to another antibody or to complement components.
Human globulin consists of monoclonal antibodies produced via the hybridoma technique, which allows for clonal selection to increase specificity for IgG or complement components. There are two types of anti-human globulin reagents: polyspecific and monospecific. Polyspecific reagents are a blend of anti-IgG and anti-C3d or anti-C3b.
There are two types of anti-human globulin reactions: the direct anti-globulin test and the indirect anti-globulin test. The direct anti-globulin test detects immunoglobulin or complement components bound to red blood cells in vivo. It is used to investigate conditions such as hemolytic disease of the fetus and newborn, autoimmune hemolytic anemia, drug-induced immune hemolytic anemia, and hemolytic transfusion reactions.
The indirect anti-globulin test facilitates the binding of immunoglobulin or complement components with red blood cells. It is used in antibody detection, screening studies, antibody identification studies, and cross-matching.
The general procedure for anti-human globulin tests involves washing the cells with NSS to remove unbound immunoglobulin or complement components before testing with anti-human globulin. In manual tube testing, IgG-sensitized red cells are added to each negative AHG test to ensure that the anti-human globulin was not neutralized due to insufficient saline washing.
In the laboratory, many facilities are now using gel technology for compatibility testing. Gel technology does not require the use of check cells or saline washing.
For false positive and false negative AHG tests, remember that a false positive can occur if the check cells are negative. To validate the result, check cells must always be positive. Other reasons for false negatives include failure to add anti-human globulin, interruption of saline washing, under-centrifugation, and failure to add patient serum.
Now, let us proceed to the different testing modalities used in blood banking. The techniques include immediate spin, incubation at 37 degrees Celsius, and the anti-human globulin test.
Compatibility testing must be done within 72 hours from the collection of the sample. The solid phase red cell adherence technique requires specialized equipment and is less subjective than manual testing.
The gel column technology is the most common technology used in blood banks. It requires specialized equipment and allows for stable results that can be reviewed later.
The inhibition and neutralization technique is useful for antibody identification. Certain soluble forms of blood group antigens exist in body fluids, including saliva, urine, and plasma.
Now, let us proceed to blood donor selection and processing. Donor screening and requirements differ for allogeneic and autologous donations.
Donors must provide identification and basic demographic data. The minimum age is 16 years old, and there is no upper limit. However, parental consent may be required for donors aged 16 to 17.
The red cell donation interval is at least eight weeks for a single unit of whole blood and greater than 16 weeks for two units. Donors must be free of major organ diseases and cancer.
Infectious disease screening is important, especially if the collection and transfusion facilities are different.
Now, let us proceed to blood collection. Blood must be collected into a sterile, closed system using aseptic techniques. The venipuncture site must be cleansed properly, and the needle size is typically 16 gauge, 1 to 1.5 inches in length.
The maximum whole blood collection is 10.5 mL per kilogram of donor weight, including samples for testing. If the donor weighs less than 110 pounds, the amount of blood collected must be proportionally reduced.
The donation should last for 8 to 15 minutes. If it exceeds 15 minutes, there is a high risk of clotting, and certain components cannot be prepared from that unit.
Adverse donor reactions can occur, including local injuries, hematomas, nerve irritation, and allergic reactions. Most reactions happen at the donation site, so donors should be observed for a certain amount of time after donation.
In the laboratory testing of donor blood, we must perform typing, including forward and reverse typing, and Rh typing. The antibody screen is performed on donor serum or plasma to detect clinically significant red cell antibodies.
Infectious disease screening includes tests for HBV, HCV, HIV, HTLV, syphilis, Chagas disease, West Nile virus, and Zika virus.
Now, let us proceed to blood component preparation. Blood component labeling is important, especially in the U.S., where they use the ISBT 128 symbol for blood unit labeling.
The labeling process includes a second check to ensure no misidentification of blood units.
Blood component manufacturing from whole blood collections can vary depending on the component being prepared.
For red blood cells, the shelf life depends on the anticoagulant used. Whole blood can be stored for 21 to 35 days, depending on the anticoagulant.
Red blood cells are expected to increase hemoglobin by 1 gram per dL and hematocrit by 3 percent.
Platelet products are stored at room temperature with gentle agitation and have a shelf life of 5 days.
FFP is stored at negative 18 degrees Celsius and is stable for 12 months.
Cryoprecipitate is used primarily for fibrinogen replacement and must be stored at negative 18 degrees Celsius.
Quality control metrics are essential for blood components, ensuring they meet specific criteria for safety and efficacy.
Now, let us proceed to the physiology and pathophysiology section, focusing on hemolytic disease of the newborn and autoimmune hemolytic anemia.
Hemolytic disease of the fetus and newborn (HDFN) is characterized by the destruction of red blood cells by maternal IgG antibodies. The antibodies must be IgG because only they can cross the placenta.
HDFN can be clinically benign, demonstrating only a positive direct antiglobulin test (DAT). The concern for HDFN depends on whether the baby is still in the womb or has been born.
While in the womb, the primary concern is anemia, as maternal antibodies destroy fetal red cells. After birth, the concern shifts to the baby's ability to conjugate bilirubin.
HDFN is categorized based on the type of antibody responsible. Before the advent of Rh immunoglobulin (Rhogam), anti-D was responsible for the majority of HDFN cases.
Other antibodies, such as anti-Kidd, anti-M, and anti-S, can also cause HDFN, with varying severity depending on the antibody involved.
Diagnosis and management of HDFN involve maternal testing during the first trimester, including Rh typing and antibody screening to detect IgG antibodies.
This concludes our review on blood group immunology and related topics. Thank you!
IgG or IgM? If necessary, we could use the TiO3 tool or tumor ethanol. Remember, the purpose of the EP and 2ME is to destroy the J chain of the IgM. If, after using DTT or tumor ethanol, the reaction is no longer present, then the antibody involved is IgM.
Next, we can use neutralization titration studies with maternal alloantibody. This is a semi-quantitative procedure; however, it is not that necessary, especially if we are not using it to predict the severity of the disease. It is not useful in predicting the severity of the disease. However, in certain cases, a critical titer of 16 to 32 or a four-fold rise is considered significant.
Now, other procedures such as phenotyping of the father and genotyping of the fetal DNA from a maternal blood sample may also be useful for diagnosis during the first trimester of pregnancy.
Next, we have fetal monitoring, testing, and treatment. Depending on antipartum and postpartum conditions, it doesn't stop after delivery.
Now, here are the techniques that might be performed during gestational testing for hemolytic disease of the newborn. First, we have Doppler fetal ultrasonography of the MCA, which is the middle cerebral artery. This is a non-invasive procedure that replaces amniocentesis. This means you are not required to collect amniotic fluid just to assess the condition of the baby. The main purpose of this technique, Doppler fetal ultrasonography, is to assess fetal anemia based on blood viscosity, specifically reduced blood viscosity.
Again, this is a non-invasive procedure that replaces the use of amniocentesis. Next, we also have cordocentesis. Cordocentesis is a procedure where we collect a fetal blood sample. We will use this fetal blood sample to test for hemoglobin, direct antibody antiglobulin test, and Rh typing. We could also test for other blood group systems. Basically, cordocentesis is just a procedure to collect a fetal blood sample for the assessment of the following parameters.
Next, we have sonography to properly collect the blood sample, which we could collect from the right side. The purpose of ultrasonography is to aid in cordocentesis. Through ultrasonography, we can also detect hydrops fetalis.
Next, we have intrauterine transfusion. This is an intervention, especially if the bilirubin level is harmful to the baby. In clinical microscopy, one of the techniques to assess the effect of hemolytic disease of the newborn on the baby is measuring the bilirubin concentration from the amniotic fluid. This bilirubin concentration is plotted on a graph, and we can determine if the concentration is in zone one, zone two, or zone three. Usually, zone three concentration requires intervention, as it is already causing severe effects on the baby. Thus, we need to perform an intervention, and one of the interventions could be intrauterine transfusion; the other is premature delivery.
Intrauterine transfusion is indicated at 24 to 26 weeks of gestation. Usually, if the baby is already showing signs of anemia, the signs of anemia can be evaluated with the use of cordocentesis, especially if the hemoglobin value is already less than 10 grams per dL.
The purpose of the intrauterine transfusion depends on the amount of blood being given. Usually, the amount of blood used is to correct anemia. If we are using large amounts of blood, the purpose is not only to provide red cells but also to clear the baby's circulation of bilirubin.
Next, we have premature delivery, which is also one of the interventions that might be done. This can be performed at 32 to 34 weeks of gestation. However, before delivery, we must ensure that the baby will survive in the outside environment. Therefore, premature delivery is not recommended if the lungs are not fully developed.
First, we have Rh testing and direct antiglobulin test on the cord blood. The interpretation of the results must take into consideration the antipartum interventions that were done, including intrauterine transfusion. Sometimes, these antipartum interventions could affect the results of postpartum testing.
A concrete example: positive infants could show a weak positive reaction. A positive infant could have a weak positive because of antipartum intervention within 72 hours after delivery. It might also be given during gestation. Gestational antibodies could cross the placenta and sensitize the baby's red cells. Since the red cells were sensitized during testing, the reaction might be weak.
So, why do we have to consider those antipartum interventions? If the hemolytic disease of the fetus and newborn is unexpected, or if the maternal antibody detection results are negative despite a positive result on cord blood, there may be a need to prepare an eluate from the cord RBCs and further evaluate the maternal serum to identify the antibody responsible for the positive result.
There may be no antibody, meaning there is no culprit antibody for that positive result. We could consider evaluating potential hemolytic disease of the newborn or the presence of maternal antibodies to a low prevalence antigen. The antibody produced against it is not that common.
Examples of low prevalence antigens or antibodies produced against low prevalence antigens could include anti-Kpa and anti-Cw.
Next, we have phototherapy, which is used for mild hemolytic disease of the fetus and newborn. This can also be used as an additional treatment for moderate and severe hemolytic disease of the fetus and newborn.
Next, we have simple or small volume transfusion. This really depends on what we are trying to correct. Usually, simple or small volume transfusion is used if anemia is the primary concern. However, we could also perform exchange transfusion. This is indicated for anemia of less than 11 grams per dL hemoglobin and a bilirubin value of greater than 20 milligrams per dL.
Exchange transfusion is necessary not just to provide red cells but also to clear bilirubin from the baby's circulation. A two-volume exchange removes 80 to 90 percent of the infant's sensitized red blood cells and also maternal antibodies, as well as 50 percent of bilirubin.
Criteria for choosing blood for neonatal intake postpartum and exchange transfusion include the following ideal attributes: it must be group O or Rh negative, antigen negative for implicated antibodies, cross-match compatible with the maternal serum, CMV safe, fresh (usually less than five to seven days old), irradiated to prevent transfusion-associated graft-versus-host disease, and negative for hemoglobin S.
However, the unit to be given for intrauterine transfusion or postpartum exchange transfusion really depends on the situation. For example, if the hemolytic disease of the newborn is not caused by anti-D, we must follow the Rh type of the baby. If it is not anti-D that causes the hemolytic disease of the newborn, then we give the positive blood or follow the Rh type of the baby.
Another important point: during my examination, remember that group O Rh negative blood is very precious. As much as possible, if there are other units that can be given to the patient, we opt to give those units because we tend to reserve group O Rh negative blood for certain situations that require its use.
In postpartum transfusion, we do not care about the mother anymore, but the point is that it must be compatible with the maternal serum. You know very well that the antibody responsible for hemolytic disease of the newborn is produced by the mother. Therefore, it must be cross-match compatible with the maternal serum, but it does not mean it has to be ABO identical with the mother.
For example, if the baby is group A and the mother is group O, we could give type-specific blood. It is only given for the baby unless the antibody responsible for hemolytic disease of the newborn is anti-A. Human antibodies can be found, so you have to make sure that the unit given should be negative for big C.
This is very important; however, again, this is a case-to-case basis. In the ASCP exam, they often give us case studies for hemolytic disease of the newborn.
Now, if the infant's blood needs to be in the presence of maternal antibody to a high prevalence antigen, antibodies to a high prevalence antigen could include anti-D. These are examples of high prevalence antigens. If blood is not available, you could use maternal wash or frozen and glycerolized red cells, and these must be irradiated. The purpose of irradiation is to prevent transfusion-associated graft-versus-host disease.
If blood is not available, we could use the mother's blood. You may also consider testing maternal siblings and searching rare donor registries for appropriate antigen-negative units.
By the way, we could also give reconstituted whole blood for exchange transfusion.
Now, how do we prevent alloimmunization? One of the techniques is the use of Rhogam. This is the very reason why Rh hemolytic disease is not common today. Rhogam is prepared from pooled human plasma from individuals who have made anti-D. It could exist as a 50 microgram microdose or a 300 microgram regular dose. The 300 micrograms regular dose protects against alloimmunization to the D antigen after exposure to 15 ml of fetal red cells or 30 ml of fetal whole blood.
During gestation, we could administer Rhogam. It is usually administered at 28 weeks of gestation to Rh negative and weak D mothers who are partial D.
HD genotyping can be used to differentiate certain weak D positive patients. There are weak D types that will not produce anti-D.
Other antipartum clinical situations where Rhogam administration is appropriate include abortion, miscarriage, and termination of ectopic pregnancy. If abortion, miscarriage, or termination of ectopic pregnancy happens during the first 12 weeks of gestation, usually only the 50 microgram microdose is given.
If the abortion, miscarriage, or termination of ectopic pregnancy happens after 12 weeks of gestation, the regular dose of 300 micrograms is given. The same dose is given in cases of abdominal trauma, after amniocentesis or cordocentesis, and if there is antipartum hemorrhage.
If Rhogam is given postpartum, the amount administered is the regular dose, and it must be given within 72 hours of delivery. The mothers should be Rh negative, weak D negative, or weak D positive. The infant must be Rh positive because there is no point in giving Rhogam if the infant is Rh negative.
Maternal serum does not demonstrate alloantibodies. If maternal serum demonstrates other alloantibody specificities, such as anti-K or anti-BK, but if the other criteria are met, it does not exclude Rhogam.
Now, how do we evaluate postpartum fetal-maternal hemorrhage and dosage of Rhogam? Each maternal sample is screened for fetal-maternal hemorrhage with a rosette test. The rosette test is a screening test capable of detecting at least 10 ml of fetal red cells.
If the rosette test is negative, it does not mean there is no fetal-maternal hemorrhage. A single vial of Rhogam is given because the sensitivity of the rosette test can only detect 10 ml of fetal red cells.
What if you have 6 ml of fetal red cells? Even if the rosette test is negative, 6 ml of fetal red cells could still sensitize the mother. Thus, it is enough to give that amount of Rhogam in a negative test.
If the rosette test is positive, you have to quantify it. You need to proceed to a quantitative test, such as the Kleihauer-Betke test or flow cytometry. The number of vials given depends on the amount of fetal-maternal hemorrhage.
For the Kleihauer-Betke test, you prepare a thin blood smear, fix it using alcohol, and expose it to an acid buffer. The fetal cells containing fetal hemoglobin are resistant to acid elution. After exposing it to the acid buffer, you stain it with eosin. Since fetal cells contain fetal hemoglobin, they resist acid elution and will appear pink because they are stained by eosin. The maternal cells will appear as ghost cells.
If we use hematoxylin as our counterstain, these ghost adult cells will be stained purple. We only count the pink cells because we are after the fetal red cells.
To calculate the number of vials of Rhogam to administer, we count a total of 2,000 cells. Out of the 2,000 cells, we take note of how many of them are fetal cells.
To solve for the volume of fetal-maternal hemorrhage in ml, we use the formula: (number of fetal cells / 2000) x 5000 ml.
Next, to solve for the number of vials of Rhogam to administer, we use the formula: (FMH in ml / 30) + 1.
Now, let's try to calculate the number of Rhogam vials to administer.
For sample one, if 26 fetal cells are seen in 200 cells counted, we first solve for the volume of fetal-maternal hemorrhage.
Volume of FMH in ml = (26 fetal cells / 2000) x 5000 = 65 ml.
Next, we solve for the number of vials of Rhogam to administer.
Number of vials = (65 ml / 30) = 2.16, which rounds to 2, plus 1. So the answer for sample one is 3 vials.
Now for sample problem number two, if the Kleihauer-Betke test result is reported to be 2.1 percent, we need to calculate how many vials of Rhogam should be administered.
The Kleihauer-Betke result is derived from the number of fetal cells in the test divided by 2000.
To find the volume of fetal-maternal hemorrhage, we multiply by 50.
For example, if the result is 2.1, then 2.1 x 50 = 105 ml.
Next, we solve for the number of vials.
Number of vials = (105 ml / 30) = 3.5, which rounds to 4, plus 1.
So the answer for sample two is 5 vials.
I hope you find these sample problems helpful.
Now, let's proceed to immune hemolytic anemias. Immune hemolytic anemias almost always demonstrate a positive DAT. This may present other serologic challenges, including determinations for ABO and Rh typing. Sometimes, the positivity of the DAT could mask the actual reaction or the actual ABO type of the patient.
To show the actual blood type of the patient, we must ensure appropriate controls are included when performing typing. We are to use low protein monoclonal Rh reagents to avoid false positive results.
Sometimes, if the red cells of the patient are coated with autoantibodies, we have to perform autoabsorption before testing. The presence of antibodies on the surface of red cells could mask forward typing.
Because of the positive DAT result, any tests with patient red cells that require the use of anti-human globulin reagent will show a positive result.
The use of monoclonal typing reagents that react at immediate spin or following incubation at 37 degrees Celsius and do not require an AHG phase of testing can be useful in red cell phenotyping.
Examples of these reagents include anti-Fya, anti-Fyb, anti-Jka, anti-Jkb, anti-S, and anti-s.
Immune hemolytic anemias can be categorized as warm autoimmune hemolytic anemia, cold agglutinin disease, paroxysmal cold hemoglobinuria, mixed type autoimmune hemolytic anemia, and drug-induced immune hemolytic anemia.
Warm autoimmune hemolytic anemia is the most common, comprising 60 to 70 percent of cases. This type of hemolytic anemia could be primary or secondary to another condition, such as leukemia or lymphoma.
Characteristics include presenting with IgG warm autoantibody. It may also demonstrate alloantibody or a combination of alloantibody and autoantibody. The antibodies will be reactive against antigens that are naturally present on the red cell.
The purpose of elution is to remove whatever antibodies are present on the surface of the red cell. Anti-IgG reacts at 37 degrees Celsius.
In 67 percent of cases, serological investigation will show positivity for both IgG and C3. Twenty percent will only show positivity for IgG, and 13 percent will show positivity for C3.
Usually, the autoantibodies are directed against high prevalence antigens. Examples of these high prevalence antigens include Rh, Landsteiner, Wiener, MNS, and Diego.
Next, let us proceed to cold agglutinin disease. This is often a favorite question in the ASCP exam. Cold agglutinin disease is responsible for around 16 to 32 percent of cases of immune hemolytic anemia.
Although this might be primary, most of the time, cold agglutinin disease is secondary, often to mycoplasma infections that result in the production of cold agglutinins.
In cold agglutinin disease, the antibody is IgM. It may also demonstrate alloantibody or a combination of alloantibody and autoantibody.
Cold antibodies facilitate red cell destruction because of their thermal range. They bind to red cells at 30 to 32 degrees Celsius. As the temperature rises, the IgM dissociates from the surface of the red cell and activates complement.
The result is that the red cells might undergo hemolysis or continue to circulate with cell-bound C3.
The specificity of antibodies responsible for cold agglutinin disease is also known as the Donath-Landsteiner antibody.
In paroxysmal cold hemoglobinuria, there is an IgG biphasic antibody that binds to red cells at low temperatures and activates complement at 37 degrees Celsius.
Whenever the blood is warm, the IgG dissociates from the red cells, leaving complement components on the surface of the red cell.
This type of immune hemolytic anemia is associated with severe hemolysis and is responsible for 8 percent of cases of hemolytic anemia.
Mixed type autoimmune hemolytic anemia has serology of both warm autoimmune hemolytic anemia and cold agglutinin disease.
Now, let's proceed to drug-induced immune hemolytic anemia. This is responsible for 10 percent of cases and has four serologic classifications: drug-dependent, drug absorption, drug-dependent immune complex, drug-independent, and non-immunologic.
First, we have drug-dependent drug absorption. This involves an IgG antibody that is only reactive with drug-bound red cells. These antibodies will only be reactive if the red cells have drugs on their surface.
Examples include penicillin, ampicillin, and cephalosporins.
Next, we have drug-dependent immune complex. In this case, the drug-antibody reacts with untreated red cells. The drug is incorporated into the test environment.
Examples include quinine, ampicillin, and second and third generation cephalosporins.
Next, we have drug-independent immune hemolytic anemia. The antibody reacts against intrinsic red blood cell antigens.
This is most frequently associated with IgG, which is why it is positive.
Lastly, we have non-immunologic immune hemolytic anemia. There is no autoantibody involved; it is due to alterations in the surface of the red cell, resulting in the attachment of proteins.
Examples of these proteins include complement components and IgG, IgM, and IgA.
That concludes the discussion on immune hemolytic anemias.