Lesson3 Flashcards
overall strength of binding.
Avidity
the strength of the binding between a single Ab and an epitope of an
antigen.
Affinity
When the Antigen-Antibody combines
Ag-Ab complex or immune complex is produced.
Red cell antigens are located
on the red cells.
Red cell antibodies
molecules in the plasma or serum.
ISBT’s stands for
The International Society of Blood Transfusion’s
Working Party on Red Cell Immunogenetics and Blood Group Terminology assigns the blood group systems.
The International Society of Blood Transfusion’s (ISBT’s)
React at body temp (37C)
IgG
can cause immune destruction of transfused red cells.
IgG
reacts best at RT (20C to 22C) or lower (4C)
IgM
The most significant immunoglobulins in transfusion medicine are
IgG and IgM.
it is performed on the patient before transfusion to detect the presence of unexpected antibodies.
Antibody screening test
Abs of the non-ABO blood group system that are considered clinically significant
Duffy, Kell, Kidd, MNS, P, and certain Rh types
needed for activation of the classical pathway.
Ca 2+ and Mg 2+
an activation of complement that is initiated by antigen-antibody complexes
Classical pathway
an antibody to an antigen that an individual lacks
Alloantibodies
(an antibody to an antigen a person has).
Autoantibodies
complement split products (C3a, C4a, and C5a) that mediate degranulation of mast cells and basophils, which results in smooth muscle contraction and increased vascular permeability.
Anaphylatoxins
products such as histamines released by basophils, mast cells, and platelets that act on the endothelium and smooth muscle of the local vasculature.
Vasoactive amines
movement of cells in the direction of the antigenic stimulus.
Chemotactic
substance (antibody or complement protein) that binds to an antigen and enhances phagocytosis.
Opsonin
cells that engulf microorganisms, other cells, and foreign particles; include neutrophils, macrophages, and monocytes.
Phagocytic cells
molecules on the cell surface that have a high affinity for a particular molecule such as antibody, hormone, or drug
Receptors
cells that engulf microorganisms, other cells, and foreign particles; include neutrophils, macrophages, and monocytes
Phagocytic cells
molecules on the cell surface that have a high affinity for a particular molecule such as antibody, hormone, or drug.
Receptors
This system acts as a filter to remove microbes and
old cells.
Mononuclear phagocyte system
secondary lymphoid organs
spleen, lymph nodes, liver, and lungs.
positive reaction is indicated by.
agglutination
negative reaction is indicated by
no agglutination.
Factors affecting the hemagglutination reaction:
Sensitization
Lattice Formation
ratio of antigen on the red cell to antibody in the serum.
SERUM-TO-CELL RATIO
an excess of unbound immunoglobulins
Prozone effect
surplus of Antigen
Postzone effect
Optimal pH for hemagglutination is ranged from
6.5-7.5
Design to determine if RBCs are coated with antibody or complement or
both.
Direct AHG
Same AHG reagents with direct AHG but with prior incubation step with plasma (serum).
Indirect AHG
can determine if RBCs have been sensitized with IgG Ab or complement or both.
Polyspecific AHG
react only with RBCs sensitized with IgG or complement
Monospecific AHG
In immunohematology, antigen– antibody reactions are measured.
qualitatively
Also referred to as the Coombs’ test.
ANTI-HUMAN GLOBULIN AND ENHANCERS
A technique for detecting cell-bound
immunoglobulin (Sensitizing Ab)
It is used to detect incomplete antibodies (IgG)
that can sensitize the RBC membrane.
Obtained from immunized nonhuman species bind to human globulins (IgG or complement).
An essential testing methodology in transfusion medicine.
ANTI-HUMAN GLOBULIN AND ENHANCERS
capable of agglutinating cells in physiological saline.
Complete antibody
bind to erythrocytes or bacteria but does not produce agglutination.
Incomplete antibody
POLYSPECIFIC AHG REAGENTS referred to as
Broad Spectrum Coombs Reagent.
An indicator of Ag-Ab reactions
A pinkish-reddish supernatant is observed after centrifuge.
Hemolysis
Hemolyzed samples are not acceptable for
serologic testing,
binding of antibody or complement components to a red cell.
Sensitization
combination of antibody and a multivalent antigen to form cross-links and result in visible agglutination
Lattice Formation
1945, they described the use of the antiglobulin test for the detection of weak and non-agglutinating Rh antibodies.
- in 1946, they described the use of AHG to detect vivo sensitization of RBCs. (Later called Direct Antiglobulin Test (DAT) of babies suffering from HDN.
Coombs and Associates
in 1947, demonstrated that the Ab activity that detected Rh Abs was associated with anti-gamma globulin fraction in the reagent.
Coombs and Mourant
Early AHG reagents were prepared using a crude globulin fraction as
the immunogen.
in 1951- presented the first indication that there might be another antibody activity present that influenced the final reaction.
Dacie
Contains only one Ab specificity
reagents prepared by separating the specificities of the polyspecific AHG reagents into individual sources of anti-IgG and anti-C3d/anti-C3b.
Preparation: uses Lab Mice
MONOSPECIFIC AHG REAGENTS
Is the product of the fusion of the mouse plasma cell and the malignant myeloma cell.
Hybridoma cells( aka immortalized Ab forming
cell)
