Diagnostic applications of immunology
Gabriel Virella in Medical Immunology, 2019
Red cell agglutination (hemagglutination). Red cell agglutination is the basis of a wide array of serological tests that can be subclassified as direct or indirect hemagglutination, depending on whether the assay involves a single step or two steps. Direct hemagglutination tests are carried out with washed red cells that are agglutinated when mixed with IgM antibodies recognizing membrane epitopes. For example, direct agglutination tests are used for the determination of the ABO blood group and titration of isohemagglutinins (anti-A and anti-B antibodies), for the titration of cold hemagglutinins (IgM antibodies which agglutinate RBC at temperatures below that of the body), and for the monospot test, useful for the diagnosis of infectious mononucleosis. This last test detects circulating heterophile antibodies (cross-reactive antibodies that combine with antigens of an animal of a different species) and induce the agglutination of sheep or horse erythrocytes. Indirect hemagglutination is used to detect antibodies that react with antigens present in the erythrocytes but that by themselves cannot induce agglutination. Usually, these are IgG antibodies that are not as efficient agglutinators of red cells as polymeric IgM antibodies. A second antibody directed to human immunoglobulins is used to induce agglutination by reacting with the red-cell bound IgG molecules, and consequently, cross-linking the red cells. The best known example of indirect agglutination is the antiglobulin or Coombs’ test that is used in the diagnosis of autoimmune hemolytic anemia.
Immune Hemolytic Anemias
Harold R. Schumacher, William A. Rock, Sanford A. Stass in Handbook of Hematologic Pathology, 2019
The patient with IgG autoantibody-mediated hemolytic anemia sometimes can be a great challenge when urgent blood transfusion is warranted. Because of “blocking” of antigenic sites by antibody, there is a special problem in typing and matching. First, proper ABO typing should be done at 37°C with a parallel control test to determine whether autoagglutination is present. If the control test is nonreactive, the results obtained with anti-A and anti-B are valid. When autoagglutination is still present, interpretation of the result can be difficult, but comparing the strength of the observed reaction may be informative. Further Rh characterization and detection of clinically significant alio- or autoantibody must be pursued. The offending antibodies are often removed by elution. Most important is the exclusion or identification of clinically significant alloantibodies in the patient’s serum. A large number of donor blood samples must be cross-matched, and the units that give the weakest reaction utilized (NB: concept of least incompatibility).
Haematological Disease
John S. Axford, Chris A. O'Callaghan in Medicine for Finals and Beyond, 2023
AIHA is caused by an autoantibody to the patient's own red cells. The antibodies are active either at body temperature (37 °C – ‘warm antibody’ = IgG) or at room temperature (15 °C – ‘cold antibody’ = IgM; Table 15.9). Cold antibody AIHA often causes red cell autoagglutination on blood films and is therefore sometimes called cold agglutinin disease. Haemolysis is usually extravascular, resulting from phagocytosis of antibody and/or complement-coated red cells within the spleen and liver.
Cold autoimmune hemolytic anemia: a rare association with triple-positive breast cancer
Published in Journal of Community Hospital Internal Medicine Perspectives, 2019
Abubakar Tauseef, Muhammad Sohaib Asghar, Maryam Zafar, Iftekhar Ahmed, Mustafa Dawood, Tooba Shaikh, Narmin Khan, Tanveer Alam
The physical examination was unremarkable except for severe pallor, lymphadenopathy in two pectoral groups of lymph nodes and the use of accessory muscles while breathing. The laboratory findings were as follows: Hemoglobin: 4.49g/dL, MCV: 80fL, total leucocyte count: 18,000 white blood cells per microliter, serum total bilirubin of 2.63umol/L with direct bilirubin of 1.30umol/L, reticulocyte count: 1.05%, LDH: 5184 U/L, while rest of the labs were within normal limits. Her red cell antibody screening, monospecific coombs C3d came out to be positive with positive direct coombs test which showed resolving the pattern of red cell agglutination after incubation at 37°C, confirming the diagnosis of Cold AIHA. The differential considerations included Non-Hodgkin lymphoma, Chronic Lymphocytic Leukemia (CLL), HIV and any systemic malignancy leading to the development of cold AIHA. Computed Tomography scan of neck, chest, abdomen, and pelvis was done to determine the definitive cause of Cold AIHA, which showed bilateral multi-level cervical lymph nodes, bilateral enlarged axillary lymph nodes and multiple diffuse lytic areas involving the whole spine, as shown in Figures 1–3.
Autoimmune hemolytic anemia: causes and consequences
Published in Expert Review of Clinical Immunology, 2022
In mixed AIHA cases [20], which are generally more severe and refractory/relapsing, clinical-laboratory features (monospecific DAT, cold agglutinin titers, autoagglutination, presence of cold agglutinin symptoms) should be evaluated at each relapse to assess the prevailing form (warm versus cold). Glucocorticoids should be given generously, and rituximab considered as an early second line, particularly in the presence of CAD features, while splenectomy is discouraged [4].
Related Knowledge Centers
- Antibody
- Autoimmune Hemolytic Anemia
- Cold Agglutinin Disease
- Hematology
- Lymphoproliferative Disorders
- Mycoplasma Pneumoniae
- Paroxysmal Nocturnal Hemoglobinuria
- Red Blood Cell
- Epstein–Barr Virus
- Idiopathic Disease