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WorksheetsTests of Cell-mediated Immunity: Intradermal Tests
Total questions: 65
Worksheet time: 33mins
Which immunoglobulin primarily mediates reactions detected by intradermal allergy tests?
IgG antibodies circulating in plasma
IgM antibodies during primary response
IgE antibodies bound to mast cells
IgA antibodies on mucosal surfaces
What is the typical outcome indicating a positive intradermal reaction at an injection site?
Blanching without any swelling
A vesicle with purulent fluid
A warm ecchymotic bruise
A raised wheal or welt
Which cells release histamine-containing granules during an immediate hypersensitivity skin reaction?
Cytotoxic T lymphocytes
Macrophages and dendritic cells
Basophils and mast cells
Neutrophils and eosinophils
During intradermal testing, which substance serves as the negative control?
Saline in sterile solution
Histamine standard dose
Epinephrine solution
Allergen extract mix
During intradermal testing, which substance serves as the positive control?
Buffered saline diluent
Patient serum sample
Histamine reference dose
Glycerinated allergen
Which site is commonly chosen for placing intradermal test injections in small animals?
Medial thigh region
Ventral abdominal wall
Lateral thorax area
Dorsal cervical neck
When should intradermal test sites typically be evaluated for reactivity after injection?
At 90 and 120 minutes
At 45 and 60 minutes
At 15 and 30 minutes
At 5 and 10 minutes
Which preparation step is recommended for the skin before placing intradermal injections?
Leave hair intact and dry
Apply alcohol and iodine
Shave hair but do not scrub
Scrub with chlorhexidine soap
Allergen selection for intradermal testing is best guided by which factors?
Randomized allergen panels
Geography and patient history
Hospital formulary restrictions only
Owner preference exclusively
Which clinical manifestation is most consistent with type I hypersensitivity on skin testing?
Lichenification with scaling crusts
Petechiae and purpura patches
Cyanosis and cold extremities
Urticaria and erythematous wheals
What measurement is commonly recorded to grade each intradermal reaction relative to controls?
Change in local temperature
Diameter of the wheal formed
Duration until peak itching
Volume of injected solution
A patient shows no response to allergens and no response to saline, but a clear wheal to histamine. How should the test be interpreted?
Test inconclusive due to artifacts
Test positive to multiple allergens
Test valid with negative allergens
Test invalid due to anergic skin
Which immunoglobulin is targeted by ELISA tests for allergen-specific antibodies in veterinary patients such as dogs, cats, and horses?
IgE antibodies specific to allergens
IgG antibodies after vaccination
IgM antibodies during primary response
IgA antibodies in mucosal secretions
The tuberculin skin test primarily detects infection by which group of organisms in animals?
Mycobacterium species causing tuberculosis
Staphylococcus species causing dermatitis
Brucella species causing abortion
Leptospira species causing leptospirosis
In the tuberculin skin test, a positive reaction is best described as which immunologic mechanism?
Neutralizing antibody blockade of toxins
Complement-mediated cytolysis of erythrocytes
Delayed hypersensitivity to tuberculin antigens
Immediate hypersensitivity to circulating IgE
For primates, where is tuberculin commonly injected during the skin test to observe reactivity?
Intradermally in the eyelid area
Subcutaneously in the forearm
Intramuscularly in the thigh
Intradermally on the abdomen
Which statement best contrasts ELISA for allergen-specific IgE with the tuberculin skin test?
ELISA detects bacterial DNA; TST detects secreted exotoxins
ELISA measures cell-mediated swelling; TST measures serum IgG
ELISA requires intradermal injection; TST requires blood draw
ELISA measures circulating antibodies; TST measures delayed skin reactivity
A herd of cattle is screened for Mycobacterium infection. Which approach aligns with standard practice for this purpose?
Measure serum IgE using allergen panels
Collect nasal swabs for rapid antigen tests
Give oral tuberculin and observe fever
Administer intradermal tuberculin at the tail base
A veterinary team observes a firm swelling 72 hours after intradermal tuberculin injection in a macaque eyelid. What is the most defensible conclusion?
The injection was placed too deeply into muscle
An acute IgE-mediated allergy to tuberculin occurred
Cell-mediated sensitization to mycobacterial antigens is present
The animal has protective neutralizing antibody levels
A dog with seasonal pruritus is tested with an ELISA panel. What result would most directly support selecting allergen-specific immunotherapy?
Detection of allergen-specific IgE to environmental proteins
Presence of high titer IgM against vaccine antigens
Positive delayed-type reaction to tuberculin antigen
Low total IgA concentration in mucosal secretions
What primary immune mechanism is identified by intradermal testing when evaluating allergic reactions?
IgA-mediated mucosal immunity
Cell-mediated cytotoxic responses
IgM-mediated complement activation
IgE-mediated hypersensitivity responses
Which material is required to perform intradermal testing accurately?
Live attenuated microorganisms
Autologous patient plasma only
Standardized extracts of antigens
Neutral saline without proteins
When assessing an intradermal test site, which parameters should be recorded to evaluate the lesion adequately?
Injection depth and needle gauge
Skin temperature and hydration
Patient age and past exposures
Erythema presence and lesion size
Basophils and mast cells contribute to the local reaction during intradermal testing primarily through which mediator?
Complement C9 forming membrane pores
Prostaglandin I2 causing vasoconstriction
Interleukin-2 driving clonal expansion
Histamine release causing inflammation
A clinic wants to screen for prior exposure to Mycobacterium using intradermal methods. Which statement best justifies this choice?
Antigen extracts are unnecessary for mycobacterial tests
Intradermal tests bypass any inflammatory pathways
Mycobacteria produce immediate IgM antibodies only
Mycobacterial antigens can be detected intradermally
Which statement best describes the purpose of a Coombs' test?
Measures complement levels during acute infection
Detects autoantibodies targeting patient tissues
Identifies bacterial antigens in patient serum
Quantifies total immunoglobulin concentration
What does a direct Coombs' reaction primarily detect on red blood cells?
Bacterial endotoxin attached to RBC surfaces
Antibodies bound to patient RBC membranes
Free antibodies circulating in patient plasma
Complement proteins attached to platelets
A positive direct Coombs' test most strongly supports which diagnosis?
Iron‑deficiency anemia without hemolysis
Immune‑mediated hemolytic disease
Hereditary spherocytosis only
Acute bacterial sepsis causing fever
What does the indirect Coombs' test detect most specifically?
Complement fragments bound to leukocytes
Antigens on donor lymphocytes in plasma
Unbound antibodies circulating in the serum
Hemoglobin released from lysed erythrocytes
In an indirect Coombs' procedure, patient serum is typically incubated with which material to screen for antibodies?
Latex beads coated with immunoglobulin
Reagent red blood cells from another source
Patient’s own washed red blood cells
Purified bacterial surface antigens
Which finding most likely yields a positive indirect Coombs' result?
Serum antibodies against self tissues present
No antibodies detected in patient plasma
Hemolysis due to mechanical valve trauma only
Only complement activation on platelets present
Which statement best defines an antibody titer?
Greatest dilution at which the sample remains positive
Average antibody concentration measured in milligrams
Volume of serum required to neutralize all antigen
Lowest dilution that first yields any visible agglutination
When are antibody titers particularly useful in practice?
Distinguishing active infection from prior exposure
Detecting acute toxin ingestion in the liver
Screening for congenital enzyme deficiencies
Confirming normal electrolyte balance after therapy
Which interpretation aligns best with a high antibody titer in a symptomatic patient?
Usually means only previous exposure long ago
Often indicates an active ongoing infection
Always guarantees complete protective immunity
Proves current antigen test is unreliable
Which clinical decision is most appropriately guided by measuring antibody titers?
Choosing the correct antibiotic susceptibility
Assessing the need for revaccination boosters
Confirming blood type for transfusion
Estimating hematocrit for anemia staging
Which immunoglobulin class primarily mediates Type I hypersensitivity reactions?
IgE antibodies bound to mast cells
IgG antibodies activating complement
IgM antibodies on B lymphocytes
IgA antibodies in mucosal secretions
A patient develops bronchoconstriction minutes after peanut exposure. Which mediator release best explains this response?
Mast cell mediators causing smooth muscle contraction
Neutrophil enzymes causing tissue necrosis
Cytotoxic T cells causing apoptosis of epithelium
NK cell perforin causing airway cell lysis
Which clinical syndrome is most consistent with a Type I hypersensitivity mechanism?
Contact dermatitis with T cell activation
Hemolytic anemia due to anti-RBC antibodies
Serum sickness with immune complex vasculitis
Allergic rhinitis with increased mucus secretion
Type II hypersensitivity is best characterized by which mechanism?
Delayed T cell–mediated cytokine injury
IgE-mediated degranulation of mast cells
Immune complexes depositing in vessel walls
Antibodies directed against self cell surface antigens
Immune-mediated hemolytic anemia (IMHA) exemplifies Type II hypersensitivity because it involves:
Eosinophil cytotoxicity to parasites
IgE crosslinking on mast cell surfaces
Host antibodies targeting red blood cells
Circulating immune complexes in glomeruli
Which antibody classes most commonly mediate Type II hypersensitivity?
IgG and IgM binding to cell antigens
IgE and IgA in mucosal tissues
IgD and IgA on naïve B cells
IgM and IgE in anaphylaxis
A transfusion reaction primarily represents which hypersensitivity type and mechanism?
Type IV with delayed T cell response
Type II with antibodies against donor cells
Type I with allergen-specific IgE binding
Type III with immune complex deposition
Immune-mediated thrombocytopenia (IMT) occurs when:
Immune complexes inflame vessel walls
Autoantibodies lead to platelet destruction
Cytotoxic T cells lyse thrombocytes
Mast cells constrict airway smooth muscle
Type III hypersensitivity reactions are defined by which process?
Deposition of antigen–antibody complexes in tissues
CD8+ T cell–mediated cytolysis of target cells
IgE-mediated release of histamine from mast cells
Direct antibody binding to cell surface proteins
Glomerulonephritis in Type III hypersensitivity is caused by:
NK cell attack on podocyte membranes
Autoantibodies lysing renal tubular cells
IgE-driven edema of Bowman’s capsule
Immune complex deposition in renal glomeruli
Systemic lupus erythematosus frequently features which immunopathologic mechanism?
CD8+ T cells destroying epidermal cells
Anti-platelet IgG causing thrombocytopenia
IgE-mediated urticaria after allergen exposure
Circulating immune complexes causing vasculitis
Which immediate physiologic change is most typical minutes after mast cell degranulation?
Increased vascular permeability leading to edema
Progressive destruction of erythrocyte membranes
Delayed activation of macrophage cytokines
Complement fixation on basement membranes
Differentiate Type I and Type II hypersensitivity by their primary targets:
Type I targets self cells via IgG; Type II targets tissues
Type I targets T cells; Type II targets parasites
Type I targets allergens via IgE; Type II targets cells
Type I targets immune complexes; Type II targets allergens
Which scenario best illustrates strategic management of anaphylaxis at first recognition?
Administer intramuscular epinephrine immediately
Order complement levels for confirmation
Begin high-volume IV antibiotics promptly
Schedule outpatient skin testing later
A dog presents with hemoglobinuria after receiving mismatched blood. What mechanism most likely explains the hemolysis?
CD4+ T cells recruit macrophages to RBCs
IgM or IgG binds donor RBCs activating complement
IgE crosslinks on basophils releasing histamine
Immune complexes deposit in renal vessels
Which mechanism best defines Type IV hypersensitivity?
T cell-mediated response against self antigens
IgE-mediated mast cell degranulation reactions
Immune complex deposition causing complement activation
Autoantibody binding to cell surface receptors
Which clinical example is most directly linked to Type IV hypersensitivity mechanisms?
Contact dermatitis from nickel exposure
Anaphylaxis after peanut ingestion
Myasthenia gravis with anti-AChR antibodies
Hemolysis from ABO incompatibility
A disease primarily involving cytotoxic T lymphocyte destruction of pancreatic beta cells exemplifies which category?
Type II hypersensitivity antibody disease
Type I hypersensitivity allergic disease
Type IV hypersensitivity autoimmune disease
Type III hypersensitivity immune complex disease
Which pair correctly matches disease with predominant immune pathway?
Type 1 diabetes—immune complex deposition
Contact urticaria—CTL-mediated cytolysis
Rheumatoid arthritis—IgE dependent degranulation
Tuberculosis—delayed-type T cell response
In contact hypersensitivity, what is the proximal effector causing tissue injury?
Eosinophil major basic protein release
Circulating IgM against haptens
Complement membrane attack complex
Activated T lymphocytes and macrophages
Which statement best characterizes lymphoma?
Tumor arising from uncontrolled lymphocyte proliferation
Autoimmune inflammation driven by self-reactive antibodies
Fibrotic replacement of lymphoid organs by collagen
Infection-induced hyperplasia that resolves spontaneously
Why is lymphoma categorized as an immune disorder?
It is caused exclusively by pathogenic bacteria
It involves dysregulated cells of the immune system
It always results from chronic allergic reactions
It only occurs with congenital complement defects
Which observation most supports a role for immune surveillance in preventing cancer establishment?
Complement classical pathway lyses gram-negative bacteria
Cytotoxic T cells recognize and eliminate transformed cells
IgE antibodies neutralize polysaccharide toxins in serum
Neutrophils phagocytose encapsulated bacteria efficiently
A patient with chronic delayed-type skin reactions and autoimmunity is most likely experiencing pathology mediated predominantly by which cells?
Hepatic Kupffer cells producing cytokines
B cells secreting neutralizing IgA
Th1 cells and cytotoxic T lymphocytes
Basophils and mast cells with IgE
Which scenario distinguishes Type IV hypersensitivity from antibody-mediated hypersensitivities?
Immediate wheal-and-flare occurs within minutes
Pathology depends on immune complex deposition
Disease improves rapidly after plasmapheresis
Onset peaks after sensitization with delayed response
Which description best matches Type I hypersensitivity?
Immune complex deposition within target tissues
Immediate reaction driven by IgE and atopy
Delayed T cell–mediated cytotoxic inflammation
Antibody binding to cell surfaces causing lysis
A patient develops hemolysis after a mismatched transfusion. Which hypersensitivity type most directly explains this event?
Type I immediate hypersensitivity with atopy
Type IV T cell–mediated delayed reaction
Type II antibody-mediated cytotoxicity
Type III immune complex deposition
Immune complex deposition leading to tissue inflammation is characteristic of which hypersensitivity type?
Type III with circulating immune complexes
Type I mediated by IgE and mast cells
Type IV mediated by sensitized T cells
Type II with antibodies to cell antigens
Which mechanism primarily underlies Type IV hypersensitivity?
IgE cross-linking causing mast cell degranulation
Deposition of antigen–antibody complexes in tissues
Complement-mediated lysis of targeted erythrocytes
Activation of sensitized T cells causing inflammation
Lymphoma is best defined as which process?
Autoantibody attack on erythrocyte membranes
Immediate hypersensitivity with systemic anaphylaxis
Uncontrolled proliferation of lymphocytes
Immune complex deposition in renal glomeruli
