BASIC PRINCIPLES OF IMMUNOLOGY AND AG-AB REACTIONS Flashcards
Any substance which when introduced to the host which can bind to a specific antibody
Antigen
any substance that can trigger an immune response
Immunogen
It may entail activation of the cellular components of immune system as well as the production of specific antibodies.
Immune Response
Two properties of an Antigen
- Specific reactivity
- Immunogenicity
_________It is an incomplete antigen. Can react with specific antibody; not immunogenic.
May become immunogenic when bound to_________
Hapten, Schlepper Molecule
It is the particular area in an antigen molecule that confers specificity to it; it is also referred to as immunodominant molecule.
Epitope/ Antigenic Determinants
Blood Group Antigens are distributed mainly on? (Give the 5)
Red cells, Tissue cells, white cells, platelets and bodily fluids
True or False
ABH antigens in tissues makes them important to be considered in organ transplants.
True
These are protein, large polysaccharide, glycoproteins or glycolipids
Blood Group Antigens
They are determined by blood group genes, and blood group phenotype.
Blood Group Antigen
Characteristics of Blood Group Antigens
Foreignness to the Host
Sufficient molecular size
Chemical Complexity
Structural Stability
How blood group antibodies produced in response to antigenic stimulation?
Exposure through pregnancy
Exposure through transfusion
Exposure through transplantation
IgM antibodies important in blood banking include:
Anti-A, Anti-B, Anti-H
Anti-I, Anti-i
Anti-M, Anti-N
Anti-Le, Anti-Lu, Anti-P
IgG antibodies important in blood banking include:
Anti-Rh, AntiS, Anti-s, Anti-Kel, Anti-Duffy, Anti-Kidd
IgA Antibodies
Anti-Le, Anti-A, Anti-B
Other name for IgM
Macroglobulin
Other name for IgA
Secretory Ig
What Ig Class is Molecular Weight 900,000
IgM
Half life of IgM
9-11 d
Half life of IgG
25-35 d
IgA half life
6-8 d
Half life of IgD
2-3d
Half life of IgE
2d
What Immunoglobulin Class can pass thru placenta?
IgG
This produced in response to antigen stimulation from the environment whose specificity is unknown / not definite (bacteria, pollen, fungi, etc.) ; non-red cell stimulated; usually IgM
Naturally Occuring
produced from red cell antigen stimulation; IgG
Immune
This are antibodies against red cell antigens, where these are differently distributed among the members of the same species; cause specific clumping of cells.
Isoagglutinins
This is associated with HTR, HDN and AIHA.
Clinically Significant
Antibodies not expected to be found in serum of patient; present in a very small human population only
Irregular
This are abs that react to red cells of the host, as well as to red cells of other individuals; produced through stimulation by bacterial or viral infections.
Autoantibodies
What antibodies that are acquired through transfusion of plasma
Passively Acquired
This abs that activates the complement , and cause red cells to lyse.
Complete Antibodies
What ab that activates the complement when it forms a complex with specific red cell antigen; IgM in nature; hemolysis is produced when specific red cells are reacted upon
Complement fixing
What abs does not activate the complement system;
Non Complement Fixing
This ab that coat the red cells, and eventually lyses them; IgM
Complete Antibodies
This ab that only coat the red cell; but not capable to lyse it.
Incomplete Antibodies
This ab that best reacts at 37 C.
Warm Antibodies
This ab that best react at 4C to ambient room temperature., (below 30C)
Cold Antibodies
Give the two Functions of Antibodies
Primary function: to bind with antigen
• Secondary functions/ biological effector functions:
Complement fixation/ activation hemolysis of red cells
Placental transfer ( IgG)
Bind on receptor sites on tissues and other cells
This are activated by the presence of foreign antigen, or abnormal autoantigen.
Immune System
Cells involved in Immune Response
APC= Macrophages, Dendritic Cells, Monocytes
Lymphocytes= T helper, T cytotoxic, B
Natural Killer, Neutrophils, Eosinophils, Basophils, Platelets
This incompatible blood type of fetus to that of mother (baby’s antigen foreign to the mother) E.g. Baby is D(+), mother is D(- )
Pregnancy
This incompatible blood type between patient (recipient) and donor blood
Transfusion
This incompatible type between patient (recipient) and donor tissue
Tissue/Organ Transplantation
This autoantibodies are produced, that detect red cell antigens
Bacterial/Viral Infection
What are the manifestations of Ag and Ab reactions?
Red cell agglutination
Hemolysis
Mix field agglutination
Give indication of a mix field agglutination
Chimeras
Mixed blood in transfusion
Acquired B phenomenon
Weak ag in subgroups
What grade reaction is Dark, Turbid Homogeneous
Grade: 0
What grading reaction is
Many tiny agglutinates
Many free cells
May not visible without microscope
W+
What grading reaction is
Many Medium sized agglutinates
Moderate number of free cells
2+
What grading reaction is
Several large agglutinates
Few free cells
3+
What grading reaction is
One large solid agglutinate
No free cells
4+
Stacked-coin formation
Rouleaux Formation
Rouleaux Formation is found in patients with:
Multiple Myeloma
Waldenstrom’s Macroglobulinemia
Hyperviscosity Syndrome
This is Interacting antigen and antibody-the antigenic determinant fit in a cleft /space formed by the combining site of the antibody (at the Fab region, formed by variable regions of light and heavy chains)
Lock and Key Concept
This Hold the Ag in the antibody combining site
Non Covalent Bonds
Non Covalent bonds includes:
Hydrogen bonds, Electrostatic bonds, Hydrophobic bonds, and Van der Waals forces
True or False
Multiple bonding ensures the Ag bound to the Ab is tight and stable
True
Stages of Red Cell Agglutination
Antibody Sensitization
Lattic Formation
This involves binding of the paratope /combining site of the Ab and the epitope/ determinant of the Ag (in a reversible reaction).
Primary Stage / Antibody Sensitization
Multiple erythrocytes with bound antibodies form a?
Lattice Formation
This is the basis of all visible agglutination reactions.
Lattice Formation
Factors Affecting Primary Stage of Reactions (Ab Sensitization)
Effect of Temperature
Effect of pH
Ionic strength
Time of Incubation
Effect of Ab Ag ratio
Optimum pH for most antigen-antibody reactions
6.5-7.5
This refers to charge concentration of the suspending (reaction) medium.
Ionic Strength
This influences the rate of formation of the antigen-antibody complex
Ionic Strength
True of False
decreasing the ionic strength of the suspending medium reduces the interfering effects of the electrostatic barrier, thus better attraction between antigen and antibody.
True
Low Ionic Strength Saline is consist of
0.2% of NaCl
This shortens incubation period of 5-15 minutes.
Low Ionic Strength Saline
To allow antigen/antibody reactions to reach equilibrium
Time of Incubation
What is the time range for the Incubation Period
15-60 minutes
In the Effect of Ag-Ab Ration, what is the optimum ratio part of Ab and Ag
80 parts of Antibody to a 1 part of Antigen
Excess in either antigen or antibody results to non occurrence of lattice formation leading to a
False Negative Result
The surface of red cells carry a negative charge due to the ionization of the carboxyl group of
NeuNac (N acetyl neuraminic acid), also called NANA or sialic acid
NeuNac (N acetyl neuraminic acid) also known as
NANA or Sialic Acid
True or False
Closer physical proximity increases antigen-antibody bridging
True
Order of effectiveness in detecting IgG antibodies:
Ficin
Papin
Bromelin
Trypsin
Water- soluble polymer used with AHG to bring sensitized cells close together and facilitate cross-linking and enhancement of agglutination reaction.
Polyethylene Glycol
Other name for Polybrene
Hexadimethrine Bromide
Positively charged macromolecule which cause non-specific aggregation of sensitized red cells with IgG antibody after incubation with LISS.
POLYBRENE (hexadimethrine bromide)
It is a red tinge of supernatant, with minimal red cell button or none at all
Hemolysis
