POPS Flashcards
Provides immediate but short lived protection from tetanus
Passive immunity via tetanus immune globin (human) (i.e. tetanus antitoxin)
Provides antibodies for a longer period of time and also provides memory cells that can be quickly turned on in the future with a booster tetanus immunization
Active immunity via tetanus toxoid
Should be given at the same time but at separate sites
Tetanus toxoid and tetanus immune globin
Should be avoided if possible because of the risk of serious anaphylactic or serum sickness reactions
Passive immunity with a heterologous antitoxin such as equine
Will stimulate the production of antitoxin, which will be protective
Tetanus toxoid
Toxins that have been detoxified by moderate heat or treatment with a chemical (e.g. formaldehyde) but have intact antigenic and immunogenic properties
Toxoids
Toxoid and toxin share
Antigenic sites
Can be used in two different ways: 1) having the ability to induce antibody synthesis and 2) having the ability to combine with an antibody. Immunogenic refers specifically to the first property
Antigenic
Previous passive immunization with heterologous (horse) antiserum (e.g. tetanus antitoxin [equine]) can stimulate the production of antibody to horse serum proteins. This can cause
Anaphylaxis
Active immunization with antigens such as tetanus toxoid does not produce sensitivity to
Horse serum protein
The lethal dose of tetanus toxin is less than the dose required to produce
Antibodies
Recovery from tetanus does not provide any immunity to
Future infections
Passive antibody will not give prolonged protection but will prevent
Tetanus short term
Digest the cell wall of many bacteria and in so doing nonspecifically prevent conjunctivitis
Lysozymes in tears
Require one to two weeks before antibody can be detected in the serum
Primary immune response
The skin protects against many different infections and hence provides
Nonspecific immunity
This type of immunity is present before birth and does not require prior exposure to a pathogen to provide protection; therefore, it provides
Innate immunity
Cell-mediated and antibody-mediated are terms that apply only to
Acquired immunity
Antibody-antigen complexes can form in the blood and be deposited in various tissues, producing pathologic changes in those tissues. More specifically, deposition of immune complexes in the renal glomeruli leads to
Glomerulonephritis
This process produces the disease called
Serum sickness
What is the name of the zone where if you remove all precipitate, the supernatant reacts with antigen?
Antibody excess zone
Will not agglutinate normal RBCs
Anti-IgG
Without washing, unbound IgG would inhibit a
Direct Coomb’s test
IgM anti-RBCs can
Agglutinate
Mother’s serum is first added to Rh-positive RBC, the RBCs are washed and then the Coombs reagent is added
Indirect Coomb’s Test
When there is so much antibody present that it coats all the antigenic sites on all the particles and there are no antigenic sites available for “bridging” antibodies we get a
Prozone
Defined as the reciprocal of the highest dilution resulting in a positive reaction
The titer
Genotype refers to the actual genes on the patient’s chromosomes, whereas phenotype refers to the physical characteristics that the patient demonstrates. For example, a homozygous MM genotype appears as an
M Phenotype
Although a population of people can sometimes have more than two alleles at one locus, one genetic locus has only two possible alleles in one person. Because M and N are alleles and S and s are alleles, M and/or an N allele must always be present, and S and/or an allele also must always be
Present
Antibody to blood group antigens stimulated by ubiquitous cross-reacting antigens found on some bacteria is called
Natural antibody
People do not have natural antibody to
Rh, MN, or Ss
Rh, MN, and Ss antigens can all elicit an antibody response. This antibody is usually
IgG
Used to detect “incomplete” or nonagglutinating antibody on RBCs. In this test, antibody to human immunoglobulin is mixed with the patient’s RBCs
Direct Coomb’s test
The antibody isotypes able to cause complement-mediated red cell hemolysis in a test tube are those able to activate complement by the classical pathway, i.e.
IgG1, IgG3, and IgM
Of these two isotypes, however, the most efficient complement activator is
IgM
IgM is the most efficient complement activator, since a single molecule can form the duplet structure necessary for C1q binding and
C1 activation
React with configurational epitopes related to the antigen-binding site of immunoglobulin molecules
Anti-idiotypic antibodies
A multivalent antigen is required to “fire off” the
Mast cell
Thus, these can not fire off a mast cell because they are univalent
Haptens
A laboratory procedure that is designed to measure specific antibodies against given antigens (allergens).
RAST assay
Theoretically, any antibody class can be measured against any antigen, but the assay is usually used to look at IgE specific for common allergens
RAST assay
Determines how much IgE antibody there is to a specific allergen
RAST assay
Measures the in vivo activity of this antibody and is therefore susceptible to many additional complicating factors such as antihistamine therapy, blocking antibody concentrations, and number and activity of mast cells
Skin test
However, there is usually a fairly good correlation between
Skin test and RAST
In the RAST assay diagram on the next page, allergen extracts are covalently linked to insoluble polysaccharide (Sepharose) beads or cellulose discs. Patient serum is mixed with these allergen-coated beads, allowing
IgE binding
After a thorough washing of the beads, radiolabeled anti-IgE is added. After a second incubation and washing, the radioactivity of the beads is
Measured
Inhibits degranulation and histamine release. One proposed mechanism is stabilization of the mast cell membrane
Cromolyn sodium
Late in an allergic attack, it is of no value since the histamine has already been released
Cromolyn Sodium
Primarily used in upper respiratory allergies since it is administered locally by inhalation
Cromolyn Sodium
Bind to the histamine-binding sites on smooth muscle and thereby competitively inhibit the binding and subsequent pharmacological action of histamine
Anti-Histamines
Almost always produced by exposure to extrinsic allergens, whereas only about 25% of asthmatic attacks are precipitated by extrinsic allergens
Allergic Rhinitis
Ashtma affects the
Lower respiratory tract
Allergic Rhinitis affects the
Upper respiratory tract
The IgG blocking antibody, if present in adequate amounts, will be more likely to bind the allergen and thereby prevent it from reaching the
IgE antibody on the mast cell surface
The switch from IgM to IgE synthesis during the process of proliferation and differentiation of B cells induced by their recognition of a given allergen requires “help” by T helper cells with
TH2 activity
TH2 cells are characterized by their release of a specific repertoire of cytokines, which includes
IL-4, 5, and 10
Largely responsible (by unknown mechanisms) for the switch from IgM to IgE synthesis
IL-4
Promotes the proliferation of all types of helper cells
IL-2
A chemotactic factor for eosinophils
IL-5
A cytokine released by antigen-presenting cells which promotes the differentiation of helper cells with TH1 activity profile
IL-12
Has been recently shown to have the ability to induce the same effects as histamine at the bronchial level
IL-13
The IgE that produces the symptoms of allergy is already bound to mast cells before it complexes with the
Allergen
When a large dose of antigen is injected into a patient with IgG or IgM antibody to the antigen, enough anaphylatoxin can be released during complement fixation to cause anaphylaxis. This occurs via
C3a and C5a
Work by competitively blocking histamine binding sites so that when mast cells release histamine, the histamine does not bind to the receptor and hence cannot cause its effects
Antihistaminic Drugs
Whether antihistaminics block the action of histamine in lung tissue is debatable. In guinea pigs, the drugs definitely block bronchial smooth muscle contraction, but in humans this action (if it occurs) is
Not clear
Block upper airway and skin effects of histamine
Antihistaminics
There are two types of leukotriene inhibitors: those that block leukotriene receptors and those that inhibit leukotriene synthesis. Either type is mostly effective on the later stages of an
Immediate hypersensitivity reaction
Leuokotrine inhibitors have mostly been used in the treatment of
Aspirin induced asthma
Hyposensitization has two major effects: on one hand, the “allergy shots” stimulate the production of
IgG blocking antibody
Binds antigen before it can get to the IgE antibody on the mast cell
IgG blocking antigen
Associated with a decrease in the specific IgE antibody to the allergen that usually parallels the increase in IgG blocking antibody
Desensitization
Takes several months, since very small doses of antigen must be given initially to prevent induction of anaphylaxis and the shots need to be repeated with increasing doses
Hyposensitization
In respiratory allergies the ideal blocking antibody would be of the
IgA isotype
Stabilizes the mast cell membrane so that histamine release is inhibited when the allergen combines with the IgE on the mast cell membrane
Cromolyn Sodium
The drug is used locally (i.e., applied by aerosol to nasal or bronchial mucous membranes)
Cromolyn sodium
It is not readily absorbed through the GI tract and is rapidly excreted, hence parenteral administration is impractical, and local application achieves highest local concentrations
Cromolyn Sodium
Cromolyn sodium is of no value in
Anaphylaxis
Have potent anti-inflammatory effects and strongly inhibit eosinophil degranulation
Glucocorticoids
Inhibit the progression of the late phase of immediate hypersensitivity reactions (particularly asthma), preventing or reducing bronchial hyperresponsiveness
Glucocorticoids
Glucocorticoids down-regulate the synthesis of
Pro-inflammatory cytokines
Reduce expression of CAMs on the vessel wall
Glucocorticoids
The modulation of CAM expression by glucocorticoids markedly alters the trafficking of human immune system cells, particularly
Neutrophils and T lymphocytes
Down-regulate the synthesis of phospholipase A2
Glucocorticoids
Thus, glucocorticoids reduce the synthesis of
Leukotrienes, prostaglandins, and platelet activation factor
In contrast, glucocorticoids upregulate the expression of lipocortin-1, a protein which has
Anti-inflammatory effects
Glucocorticoids administered by inhalation are now recommended for the treatment of
Chronic Ashtma
Relaxes smooth muscles in the lung by stimulating the -adrenergic receptors and hence can directly reverse constriction of the bronchioles and bronchi
Epinephrine
Is usually given subcutaneously (SC); in severe cases, it can be given intravenously (IV) for faster action, or even into the heart if the patient has no immediately accessible veins
Epinephrine
