| The diagram on the right shows two antibody response curves. Match the terms on the left with the corresponding numbers in the diagram. | View Page |
| Anti-Rho immune serum is administered to: | View Page |
| Rh immune globulin therapy in postpartum women provides: | View Page |
| In HDN which of the following antigen-antibody reactions is occurring: | View Page |
| Which of the following best describes the direct antiglobulin test principle: | View Page |
| When AHG or Coombs serum is used to demonstrate that red cells are antibody coated in vivo, the procedure is termed: | View Page |
| The prozone effect can be described by all of the following except: | View Page |
| Match each blood type with the corresponding antibody you would find in its serum: | View Page |
| Avidity is best described by which of the following statements: | View Page |
| Which of the following options gives in order from most to least important, the factors you would use to select blood for a transfusion: | View Page |
| The use of cells with known blood groups to confirm ABO typing is known as: | View Page |
| Essential components of compatibility testing include all of the following except : | View Page |
| Patients with antibody to the following antigen are immune to Hepatitis B: | View Page |
| What is Coombs sera comprised of: | View Page |
| The Western Blot Assay is used as a confirmatory test for which of the following: | View Page |
| Autologous blood must be tested for which of the following before transfusion: | View Page |
| Which of the following might cause a false positive indirect antiglobulin test: | View Page |
| A solution of gamma globulins containing anti-Rh (D) is given to an Rh (D) negative mother to: | View Page |
| To detect the presence of blocking antibodies fixed on the red cells of a newborn infant: | View Page |
| In preparing red cells for any elution method , one must be particularly careful to: | View Page |
| Which of the following is the proper temperature to use when crossmatching in the presence of a cold antibody: | View Page |
| A primary immune response is generally associated with which of the following antibodies: | View Page |
| Match antibody group with corresponding descriptor: | View Page |
| Which of the following antibodies is predominantly associated with the secondary antibody response: | View Page |
| Which of the following antigen groups is closely related to the ABO system: | View Page |
| A false-negative reaction while performing the DAT technique may be the result of: | View Page |
| The two or three reagent cells used for antibody screening will detect which of the following: | View Page |
| The prozone effect ( when performing a screening titer) is most likely to result in: | View Page |
| Which of the following antibody types is chiefly seen in the primary immune response: | View Page |
| Which of the following antibody types is chiefly seen in the secondary immune response: | View Page |
| A hapten is only antigenic when it is coupled with which of the following: | View Page |
| The reaction that occurs when a soluble antigen is mixed with its specific antibody is termed: | View Page |
| The term TITER ( as it applies to the measurement of antibodies) is best defined as: | View Page |
| This question refers to results of the classical complement fixation test; match the result on the left with the presence or absence of hemolysis on the right. | View Page |
| Which of the following would be considered most significant as it relates to serological testing: | View Page |
| The History of the ABO System (cont.) Landsteiner, knowing that none of his subjects had been immunized, realized that “natural” antibodies must develop which are directed against antigens not present on the red cells. Individuals with “A” antigens on their red cells had sera containing “Anti-B” antibody. Individuals with “B” antigens had sera containing “Anti-A.” “AB” individuals had sera with no ABO antibodies present and “O” individuals’ sera contained “Anti-A” and “Anti-B.” Sera from group O individuals may contain a separate antibody, “Anti-A,B.” Anti-A,B possesses serologic activity not found in mixtures of Anti-A and Anti-B. Anti-A,B sera will agglutinate A, B, and AB cells. It is particularly useful in detecting weak A and B antigens. See the table on the next page. | View Page |
| Importance of Understanding the ABO System While the predictability of ABO antibodies in persons lacking the corresponding antigen makes the ABO blood group system an easy one for testing purposes, it can be treacherous as far as transfusion is concerned. If a patient receives cells containing A or B antigens and his/her serum contains the corresponding antibody, the donor cells will be destroyed almost immediately with severe and sometimes fatal transfusion reaction. It is, therefore, of utmost importance to thoroughly understand the ABO blood group system. Compatibility of the ABO system is essential for all other pre-transfusion testing. | View Page |
| ABO Antibodies In most other blood group systems, antibody may be formed after an individual has been immunized by an antigen that is missing from his or her red cells; perhaps as the result of pregnancy or transfusion. In the ABO system, when the antigen is missing from the cells, the corresponding antibody will predictably be found in the serum and must be found before determining the ABO type. There are few exceptions to this rule and any exception must be explained before the true ABO blood type can be determined. | View Page |
| "Immune" ABO Antibodies A person exposed to a specific immunizing event may produce “immune” ABO antibodies of the same specificity as the “naturally” occurring antibody, but with different biological behavior. Such immunizing events include pregnancy with an ABO incompatible fetus or transfusion of ABO incompatible red cells. After immunization, the subject’s antibody may increase in titer and/or avidity, develop powerful hemolyzing properties, or become more active at 37ºC. | View Page |
| A1 and A2 The most common classifications are A1 and A2. These account for over 99% of group A bloods. Of this 99%, A1 compromises approximately 80%. Commercial anti-A typing serum does not differentiate between A1 and A2 cells. A1 cells contain “A” antigen and “A1” antigen. A2 is not really a unique antigen. It is thought to be simply “A” antigen with no “A1” antigen. Several preparations are available that will react with A1 cells, but not other subgroups of A. An extract of the seeds of the plant, Dolichos biflorus has specific anti-A1 activity. “Absorbed anti-A” serum can also be prepared. To do this, the anti-A from group B people is absorbed with A2 cells. Anti-A is removed and a second antibody that reacts only with A1 cells remains. Anti-A1 can also be found as a separate antibody in the sera of A2 and A2B individuals. | View Page |
| Rare Subgroups of A Other rare subgroups of A exist. These comprise less than 1% of the total pool of A genes. Of these rare types, A3 is the most common, but Ax, Aend, and Ael have also been identified. In subgroup A3, the red blood cells characteristically give a “mixed field” agglutination pattern when tested with anti-A and anti-A,B. Small clumps of agglutinated cells are present among large numbers of cells which absorb the antibody to their surface but are not agglutinated by it. | View Page |
| Why Knowledge of A Subgroups Is Important For Laboratorians For the most part, subgroups are merely of academic interest, but occasionally they present clinical problems. The antigen may be so weak that it is not detected and the red cells are mistyped as group O. This is especially dangerous if the cells are those of a donor. Problems may arise because the serum of an A2 or A2B, A3 or Ax individual might contain anti-A1. This antibody may be detected in serum typing and cause confusion. You would not expect to find a person with A antigen on his red cells and anti-A in his serum. Anti-A1 is produced by about 1-2% of group A2 persons and about 25% of group A2B persons. Subgroups may be determined by reactions with antisera as seen in the table on the next page. | View Page |
| Why may the presence of A subgroups cause ABO typing discrepancies? | View Page |
| Agglutination Reactions Antibodies of the ABO system cause agglutination of saline-suspended red cells at 4°C to 20°C. Heating to 37° weakens the reaction. “Naturally” occurring ABO antibodies may not be strong enough to agglutinate cells without centrifugation. Thus, testing serum for the presence of anti-A or anti-B has classically been performed using the tube system in which serum and cells added to a test tube are centrifuged and then evaluated for agglutination. A slide test has also been performed for forward reactions. Although tube tests are still in wide use, newer systems utilizing other technology such as gel agglutination are becoming more prevalent. The image on this page illustrates agglutination reactions observed with the tube system, from 4+ in the topmost image, to 0 in the lowest image. ABO reactions should be strong. Weak or missing reactions occur, but must be "resolved" before blood products can be released.4+ agglutination: Red blood cell button is a solid agglutinate; clear background.3+ agglutination: Red blood cell button breaks into several large agglutinates; clear background.2+ agglutination: Red blood cell button breaks into many medium-sized agglutinates; clear background; no free red blood cells.1+ agglutination: Red blood cell button breaks into many small clumps barely visible macroscopically; background is turbid; many free red blood cells.Negative: No agglutinated red blood cells present; red cells are observed flowing off the red blood cell button during the process of grading.Other reaction which may occur are the mixed-field reaction, in which mixtures of agglutinated and unagglutinated red blood are present; and hemolysis, in which red cells are hemolyzed by the antibody. Both of these patterns are considered positive reactions. | View Page |
| Automated Systems An increasing number of transfusion services are using automated blood banking systems. These systems may employ either solid phase or gel techniques. Use of automation may increase productivity, reduce costs, and, by decreasing the number of manual steps in the testing process, potentially reduce errors. | View Page |
| Example of an ABO discrepancy The composite image shown on the right illustrates the ABO typing reactions that were obtained for a patient. This particular case illustrates an ABO discrepancy. An ABO discrepancy occurs when the results of forward and reverse typing do not match. The reactions shown are described below in descending order:Patient red cells with reagent anti-A: negative reaction.Patient red cells with reagent anti-B: 4+ agglutination.Patient red cells with reagent anti-D: 4+ agglutination.Patient serum with reagent A1 red cells: negative reaction.Patient serum with reagent B red cells: negative reaction.This patient forward types as a group B, but reverse types as a group AB. (A group B patient should have anti-A. This patient demonstrates neither anti-A nor anti-B, similar to an AB patient). Further workup is necessary to determine the ABO type since the forward and back typing do not match. In this case, incubation at 40 C demonstrated the presence of weakened anti-A. The patient was therefore typed as group B. This case is an example of an ABO discrepancy which was due to a "missing" anti-A antibody. This could be due to old age, severe illness or immunosuppression. Although evaluation of ABO discrepancies is beyond the scope of this course, it is important to note that all ABO discrepancies must be resolved before blood products can be released for transfusion.This patient is Rh (D) positive, as evidenced by the strong agglutination of his cells with reagent anti-D antibody. | View Page |
| Description of Specialties (4) Specialists in cytogenetics detect chromosome abnormalities and genetic disorders. Cytogenetics counseling may only be performed by an individual licenses in the cytogenetics specialty at the director level.
Specialists in molecular genetics analyze DNA and RNA to find disease-related genotypes, mutations, and phenotypes in order to detect or predict disease and identify carriers.
Specialists in histocompatibility test to determine tissue compatibility, prevent infections, and investigate and post-transplant problems. Techniques include blood typing, HLA typing, HLA antibody screening, disease markers, flow cytometry, crossmatching, HLA antibody identification, lymphocyte immunophenotyping, immunosuppressive drug assays, allogenic, isogeneic and autologous bone marrow processing and storage, mixed lymphocyte culture, stem cell culture, cell
mediated assays, and assays for the presence of cytokines.
Specialists in andrology and embryology examine gametes and embryos, including production, morphology, number, and motility, to address issues of fertility and infertility. | View Page |
| Match the cells with their characteristics. | View Page |
| Glossary of Terms A through M. Antibody - A modified type of serum globulin synthesized by lymphoid tissue in response to antigenic stimulus. By virtue of specific combining sites each antibody reacts with only one antigen. Anucleate - Having no nucleus. Azurophilic granules - The well-defined large reddish granules (lysosomes) which may be present in large lymphocytes. They are called "azurophilic granules" because they stain blue with the azure stains which were originally used. Basophilic granules - Specific granules present in the cytoplasm of basophils. These granules are large and stain purple-black due to their strong affinity for basic stain. B-cell - Bone marrow derived lymphocytes which produce humoral antibodies. Biconcave - Having two concave surfaces. Cellular Immunity - The capacity of a small proportion of lymphoid population to exhibit response to a specific antigen. Chromomere - The centrally located granular portion of the platelet. Clone - A population of cells descended from a single cell. Delayed Hypersensitivity - (part of cellular immunity) that develops slowly over a period of 24-72 hours after an antigenic stimulus. It consists of an accumulation of cells around small vessels and/or nerves. Example: Tuberculin skin test reaction. Digestive Enzyme - A substance that catalyzes or accelerates the process of digestion. Eosinophilic Granules - Specific granules present in the cytoplasm of eosinophils. These granules are large, refractile spheres which stain reddish-orange due to their strong affinity for acid stain. Erythrocyte (red blood cell, RBC) - One of the elements found in peripheral blood. Normally the mature form is a non-nucleated, circular, biconcave disk adapted to transport respiratory gases. Fixed Macrophage - A phagocyte that is non-motile. Free Macrophage - An ameboid phagocyte present at the site of inflammation. Graft Rejection - A transplanted tissue that is rejected by the body's antibodies. Graft vs. Host Reaction - A complication that occurs when an implanted piece of tissue, which contains antibodies, rejects the host's tissue. Granulocyte - A leukocyte which contains granules in its cytoplasm, i.e., neutrophilic, eosinophilic, or basophilic granules. Half-life - is the length of time it takes for half of the cells circulating at a given time to leave the blood for the tissues. Hemocyte - Any blood cell or formed element of the blood. Hemostasis - A mechanism of the vascular system to arrest an escape of blood. It involves an interaction between blood vessels, platelets, and coagulation. Heparin - A mucopolysaccharide acid which, when present in sufficient amounts, functions as an anticoagulant by inhibiting thrombin. Histamine - A powerful dilator of capillaries and a stimulator of gastric secretions. Humoral Immunity - Acquired immunity produced after response to an antigenic stimulus in which B cells produce circulating antibodies. Hyalomere - the clear, blue non-granular zone surrounding the chromomere of a platelet. Immune Response - The interaction of a cell and an antigen that results in a proliferation of the cell and a capacity to produce antibodies. Isotonic Fluid - A fluid whose elements have an equal osmotic pressure. Leukocyte (white blood cell, WBC) - One of the formed elements of the blood; involved primarily with the body's defense. Lysosome - A microscopic body within cell cytoplasm; contains various enzymes, mainly hydrolytic, which are released upon injury to the cell. Megakaryocyte - A giant cell of the bone marrow from which platelets are derived. Mononuclear - A cell having a single nucleus. | View Page |