[11] CHAPTER V LESSON 1 Flashcards
AHG’s obtained from immunized nonhuman species bind to human globulins such as (?] either free in serum or attached to antigens on red blood cells (RBC’s).
IgG or complement
2 major types of blood group antibodies:
IgM
IgG
- bind to corresponding antigen
IgM
directly agglutinate RBCs suspended in saline
IgM
- “nonagglutinating” or “incomplete antibodies”
IgG
because their single monomer structure is too small to directly agglutinate sensitized RBCs
IgG
described the use of the antiglobulin test for the detection of weak and nonagglutinating Rh antibodies in serum.
Coombs, Mourant, and Race
described the use of AHG to detect in vivo sensitization of the RBCs of babies suffering from HDFN.
Coombs and coworkers
described the principle of the test
Moreschi
Kell blood group antibodies and assoc. antigen
Moreschi
Reported weeks after the Coombs had described the test
Moreschi
- RBCs has been sensitized by an antibody
Hemagglutination
Early AHG reagents were prepared using a (?) as the immunogen.
crude globulin fraction
demonstrated that the antibody activity that detected Rh o antibodies were associated with the anti-gamma globulin fraction in the reagent.
Coombs and Mourant
: Observed that different reaction patterns were obtained when dilutions of AHG were used to test cells sensitized with warm as compared to cold antibodies.
Dacie
published data showing that the reactivity of AHG to cells sensitized with warm antibodies resulted from anti-gamma globulin activity, whereas antinongamma globulin activity was responsible for the activity of cells sensitized by cold antibodies.
Dacie and coworkers
was shown to be beta globulin and had specificity for complement
nongamma globulin component
Later studies revealed that the complement activity was a result of
C3 and C4
can be used to detect RBCs sensitized with IgG alloantibodies, IgG autoantibodies, and complement components.
antiglobulin test
can occur either in vivo or in vitro:
Sensitization
is detected by a one stage procedure
In vivo sensitization
In vivo sensitization ex.
Direct antiglobulin test (DAT)
The use of AHG to detect [?] of RBCs is a two-stage technique
in vitro sensitization
In vitro sensitization ex.
Indirect antiglobulin test (IAT)
ANTIHUMAN GLOBULIN REAGENTS
Defined by
Food and Drug Administration (FDA) and Center for Biologics Evaluation and Research (CBER)
- contain antibody to human IgG and to the C3d component of the human complement.
- Polyspecific AHG
Other anticomplement antibodies, such as anti-C3b, may also be present.
- Polyspecific AHG
- contain only one antibody specificity: either anti-IgG or antibody to specific complement components (C3b or C3d).
- Monospecific AHG
Licensed monospecific AHG reagents in common use are
- Monospecific AHG
antiIgG and anti-C3b,-C3d.
Contain no anticomplement activity
a. Anti-IgG
Contain antibodies specific for the Fc fragment of the gamma heavy chain of the IgG molecule
a. Anti-IgG
- reactive against only the designated complement components and contain no activity against human immunoglobulins
b. Anticomplement
Anti-C3b and anti-C3d reagents
Monospecific anticomplement reagents: Often a blend of
b. Anticomplement
monoclonal anti-C3b and monoclonal C3d.
FDA Licensed Antihuman Globulin Reagents
Polyspecific
Monospecific
Anticomplement
Polyspecific
1. Rabbit Polyclonal
2. Rabbit/murine monoclonal blend
Monospecific
1. Anti-IgG (Rabbit polyclonal)
2. Anti-IgG (Gamma-done AHG)
Anticomplement
Anti-C3d
Contains anti-lgG and anti-C3d (may contain other anticomplement and other antiimmunoglobulin antibodies)
Rabbit Polyclonal
Rabbit/murine monoclonal blend
Contains a blend of (?) is a murine monoclonal IgM antibody
rabbit polyclonal antihuman IgG and Anti-C3d
Contains anti-IgG with no anticomplement activity
Anti-IgG (Rabbit polyclonal)
Murine monoclonal IgM antibody secreted by a hybridoma cell line
Anti-IgG (Gamma-done AHG)
The main component of this reagent is a murine monoclonal antibody to C3d.
Anti-C3d
will cause the agglutination of red blood cells coated with human C3d and/or C3b complement components.
Anti-C3d
- Involves injecting human serum or purified globulin into laboratory animals such as rabbits.
Classic method of AHG production
The (?) behaves as foreign antigen, the rabbit’s immune response is triggered, and an antibody to (?) is produced.
human globulin
human globulin
- Human IgG injected into a rabbit- results in
anti-IgG production
- Human complement components injected into a rabbit result in
anticomplement
PREPARATION OF AHG
This type of response produces a
polyclonal antiglobulin serum
can be made using polyclonal or monoclonal antibodies.
Polyspecific AHG
The two types of antibody production processes are very different from one another, yielding two very different advantages and disadvantages in their usage.
Polyspecific AHG
is usually prepared in rabbits.
Polyclonal AHG
are produced by immunizing one colony of rabbits with human immunoglobulin (IgG) antigen and another colony with human C3 antigen.
Conventional polyspecific antiglobulin reagents
Because of the heterogeneity of IgG molecules, using serum from many donors to prepare the pooled IgG antigen to immunize the rabbits and the pooling of anti-IgG from many immunized rabbits is essential in producing polyclonal reagents for routine use that are capable of detecting the many different IgG antibodies.
Polyclonal AHG
This is an advantage of using anti-IgG of polyclonal origin for antiglobulin serum.
Polyclonal AHG