MICROBIOLOGY 2215 CSCC ACTUAL EXAM
SOLVED QUESTIONS COMPLETE
PREPARATION RESOURCE
●● Define allergen
Answer: the antigen to which allergic individuals are sensitive
●● Define allergy
Answer: hypersensitivity reaction due to a normally harmless,
environmental substance
●● What are the four types of hypersensitivities?
Answer: Type I: Immediate IgE-mediated
Type II: Cytotoxic
Type III: Immune complex-mediated
Type IV: Delayed cell-mediated
●● What antibody classes and lymphocytes are involved in each type of
hypersensitivity?
Answer: type I: IgE antibodies
type II: complement system and antibody dependent cellular toxicity
type III: IgG or IgM antibodies
,type IV: T cell receptors
●● Type I: what three steps occur upon first exposure to the antigen?
Answer: 1. B-cell Activation: B cell binds to allergen and is activated by
helper T cell
2. Proliferation, class-switching and differentiation: the B cells
differentiate into IgE-producing plasma cells and memory cells.
3. Sensitization: Fc portions of IgE antibodies bind to mast cell receptors
●● Type I: what three steps occur upon secondary (or subsequent)
exposure?
Answer: 1. Cross-linking of cell-bound IgE: cross-linking by allergen
causes the mast cell to degranulate.
2. Degranulation and release of mediators: histamine and other
mediators are released.
3. Allergy symptoms: symptoms of allergy include sneezing and runny
nose.
●● How does immunotherapy treat Type 1 hypersensitivities and lead to
desensitization?
,Answer: by injecting someone with extremely dilute concentration of
allergen.
allergen gradually increased over time and individual gradually become
less sensitive.
●● How does omalizumab treat Type 1 hypersensitivity?
Answer: by binding to the Fc portion of IgE, which blocks the
attachment to mast cells and basophils
●● What are the four main blood types in which antigens are associated
with each blood type?
Answer: Type A - A antigens
Type B - B antigens
Type AB - A antigens and B antigens
Type O - no antigens
●● How does the Rh factor cause hemolytic disease and pregnant
women?
Answer: the basis of the disease is when there is incompatibility of Rh
factor between the mother and child
Rh antibodies form in Rh- mothers who are pregnant with Rh+ fetuses
, ●● What does RhoGAM do?
Answer: Destroys fetal Rh+ RBCs that have crossed the placenta
●● What are some common causes of Type III hypersensitivities?
Answer: bacterial, viral, protozoan infections and also from inhaled dust,
bacteria, injected medications.
●● Explain the process of Type IV hypersensitivities.
Answer: delayed hypersensitivities that are caused by T cell responses
that are slowly developing an antigen specific T cell response
●● What are some examples of Type IV hypersensitivities?
Answer: contact dermatitis, tissue damage, positive tuberculosis skin
test, poison ivy
●● How does the TB test work?
Answer: injected right beneath skin, 48-72 hour incubation
+ = hard red area, - = no reaction
●● What markers are used as the basis of tissue graft/organ transplant
rejection?
Answer: MHC class 1 differences between the donor and recipient
SOLVED QUESTIONS COMPLETE
PREPARATION RESOURCE
●● Define allergen
Answer: the antigen to which allergic individuals are sensitive
●● Define allergy
Answer: hypersensitivity reaction due to a normally harmless,
environmental substance
●● What are the four types of hypersensitivities?
Answer: Type I: Immediate IgE-mediated
Type II: Cytotoxic
Type III: Immune complex-mediated
Type IV: Delayed cell-mediated
●● What antibody classes and lymphocytes are involved in each type of
hypersensitivity?
Answer: type I: IgE antibodies
type II: complement system and antibody dependent cellular toxicity
type III: IgG or IgM antibodies
,type IV: T cell receptors
●● Type I: what three steps occur upon first exposure to the antigen?
Answer: 1. B-cell Activation: B cell binds to allergen and is activated by
helper T cell
2. Proliferation, class-switching and differentiation: the B cells
differentiate into IgE-producing plasma cells and memory cells.
3. Sensitization: Fc portions of IgE antibodies bind to mast cell receptors
●● Type I: what three steps occur upon secondary (or subsequent)
exposure?
Answer: 1. Cross-linking of cell-bound IgE: cross-linking by allergen
causes the mast cell to degranulate.
2. Degranulation and release of mediators: histamine and other
mediators are released.
3. Allergy symptoms: symptoms of allergy include sneezing and runny
nose.
●● How does immunotherapy treat Type 1 hypersensitivities and lead to
desensitization?
,Answer: by injecting someone with extremely dilute concentration of
allergen.
allergen gradually increased over time and individual gradually become
less sensitive.
●● How does omalizumab treat Type 1 hypersensitivity?
Answer: by binding to the Fc portion of IgE, which blocks the
attachment to mast cells and basophils
●● What are the four main blood types in which antigens are associated
with each blood type?
Answer: Type A - A antigens
Type B - B antigens
Type AB - A antigens and B antigens
Type O - no antigens
●● How does the Rh factor cause hemolytic disease and pregnant
women?
Answer: the basis of the disease is when there is incompatibility of Rh
factor between the mother and child
Rh antibodies form in Rh- mothers who are pregnant with Rh+ fetuses
, ●● What does RhoGAM do?
Answer: Destroys fetal Rh+ RBCs that have crossed the placenta
●● What are some common causes of Type III hypersensitivities?
Answer: bacterial, viral, protozoan infections and also from inhaled dust,
bacteria, injected medications.
●● Explain the process of Type IV hypersensitivities.
Answer: delayed hypersensitivities that are caused by T cell responses
that are slowly developing an antigen specific T cell response
●● What are some examples of Type IV hypersensitivities?
Answer: contact dermatitis, tissue damage, positive tuberculosis skin
test, poison ivy
●● How does the TB test work?
Answer: injected right beneath skin, 48-72 hour incubation
+ = hard red area, - = no reaction
●● What markers are used as the basis of tissue graft/organ transplant
rejection?
Answer: MHC class 1 differences between the donor and recipient
