TOPIC 3 - P1 Flashcards
Antihuman Globulin Test AKA ________
Coombs’ test
Principle: antihuman globulins (AHGs) obtained from immunized nonhuman species bind to human globulins such as IgG or complement, either free in serum or attached to antigens on RBCs
Coombs’ test
2 major types of blood group antibodies
IgM and IgG
- large pentamer structure
- directly agglutinate RBCs suspended in saline
IgM
- termed nonagglutinating, or incomplete antibodies,
- monomer structure is too small to directly agglutinate sensitized RBCs
IgG
AHG that contains _____ to RBCs sensitized with IgG antibodies allows for ______ of these sensitized cells
anti-IgG ; hemagglutination
_____ detect IgG or complement-sensitized RBCs
Antiglobulin tests
(HISTORY OF THE ANTIGLOBULIN TEST)
Before, only _______ were detected. AGT permitted the detection of nonagglutinating IgG antibodies and led to the discovery and characterization of many new blood group systems.
IgM antibodies
(HISTORY OF THE ANTIGLOBULIN TEST)
_____, Coombs and associates described the use of the _______ for the detection of weak and nonagglutinating Rh antibodies in serum
1945 ; antiglobulin test
(HISTORY OF THE ANTIGLOBULIN TEST)
_____, Coombs and coworkers described the use of _____ to detect in vivo sensitization of the RBCs (later AKA direct antiglobulin test [DAT]) of babies suffering from __________
Although the test was initially of great value in the investigation of _____, its versatility for detecting other IgG blood group antibodies soon became evident.
1946 ; AHG ; hemolytic disease of the newborn (HDN)
Rh HDN
(HISTORY OF THE ANTIGLOBULIN TEST)
weeks after Coombs had described the test, _________ antibodies and the associated antigen were reported
Kell blood group system
(HISTORY OF THE ANTIGLOBULIN TEST)
Although Coombs and associates were instrumental in introducing the antiglobulin test to blood group serology, the principle of the test had in fact been described by ____ in ____
Moreschi ; 1908
(HISTORY OF THE ANTIGLOBULIN TEST)
1908: Moreschi’s studies used ________ serum to agglutinate rabbit RBCs that were sensitized with low nonagglutinating doses of _________
rabbit antigoat ; goat antirabbit RBC serum
(HISTORY OF THE ANTIGLOBULIN TEST)
Early AHG reagents: prepared using a -___________ as the immunogen
Crude globulin fraction
(HISTORY OF THE ANTIGLOBULIN TEST)
______: _______ demonstrated that the antibody activity that detected Rh antibodies was associated with the ________ fraction in the reagent
1947 ; Coombs and Mourant ; anti–gamma globulin
(HISTORY OF THE ANTIGLOBULIN TEST)
______: _____ presented the first indication that there might be another antibody activity present that influenced the final reaction
1951 ; Dacie
(HISTORY OF THE ANTIGLOBULIN TEST)
observed that different ________ were obtained when dilutions of AHG were used to test cells sensitized with _____ as compared with cold antibodies
reaction patterns ; warm
(HISTORY OF THE ANTIGLOBULIN TEST)
_____: Dacie and coworkers published data showing that the reactivity of AHG to cells sensitized with warm antibodies resulted from _________ & ________ was responsible for the activity of cells sensitized by cold antibodies
1957 ; anti–gamma globulin activity ; anti–nongamma globulin activity
____________ was shown to be beta globulin and had specificity for complement
nongamma globulin component
Sensitization can occur either _____ OR ______
in vivo or in vitro
- two-stage technique (With Incubation)
- use of AHG to detect in vitro sensitization
of RBCs
Indirect Antiglobulin Test (IAT)
- one-stage procedure (Without Incubation)
- use of AHG to detect in vivo sensitization of RBCs
Direct Antiglobulin Test (Dat)
Antihuman Globulin Reagents can be:
can be polyspecific or monospecific
- contain antibody to human IgG and to the C3d component of human complement
- can facilitate agglutination when RBCs have been sensitized with IgG or C3d or both.
Polyspecific AHG reagent
the disadvantage of this reagent is that, it may contain antibody activity to kappa and lambda light chains common to all immunoglobulin classes, thus reacting with IgA or IgM molecules
Polyspecific AHG reagent
- contain only one antibody specificity: either anti-IgG or antibody to specific complement components [C3b or C3d (i.e., anticomplement)]
- Anti-IgG: contain no anticomplement activity
- contain antibodies specific for the FC
fragment of the gamma heavy chain of the IgG molecule - Anticomplement: reactive against only the designated complement components
- contain no activity against human immunoglobulins
- often a blend of monoclonal anti-C3b and monoclonal anti-C3d
Monospecific
(Preparation of AHG)
classic method of AHG production involves injecting ______ or _______ into laboratory animals such as rabbits
human globulin behaves as _______ the rabbit’s immune response is triggered, and an antibody to human globulin is produced
human serum ; purified globulin
foreign antigen
(Preparation of AHG)
_______: mixture of antibodies from different plasma cell clones
recognize different _________ (epitopes), or the same portion of the antigen but with different affinities
Polyclonal antibodies ; antigenic determinants