16 June 2026
ACAAI Review for the Allergy & Immunology Boards
PREP EXAM 2026/2027 LATEST EXAM TESTBANK UNDER NEW
GUIDELINE 450 QUESTIONS AND CORRECT ANSWERS PERFECT
TO PASS 2026 ACAAI TEST EXAM
Small-molecule antigen requires covalent linkage to a larger carrier to stimulate adaptive immune
response. The process is achieved in collaboration between hapten-specific B cells and carrier-
specific T cells. This is the basis of developing conjugated vaccines. - correct answer-What is the
hapten-carrier effect?
SEB and SEC from Staphylococcus aureus cause food poisoning. TSST from Staphylococcus aureus
and SPE-C from Streptococus pyogenes cause toxic shock syndrome. - correct answer-What are the
common superantigens and related diseases?
Natural killer T (NKT) cells recognize lipid antigens, and the CD1 molecule is involved. - correct
answer-Which type of T cell recognizes lipid antigens and what molecule is involved?
Protein antigens are T-cell dependent. Polysaccharide, nucleic acid, and lipids are T-cell
independent. - correct answer-Which antigens are T-cell dependent and which are T-cell
independent?
On the MHC class I molecule, α3 is the binding site for CD8. On the MHC class II molecule, β2 is the
binding site for CD4 - correct answer-What is the binding site for CD4 on the MHC class I molecule?
What is the binding site for CD8 on the MHC class II molecule?
On the MHC Class I molecule, α1 and α2 make up the peptide binding cleft. On the MHC class II
molecule, α1 and β1 make up the peptide binding cleft. - correct answer-Which chain makes up the
peptide binding cleft in MHC class I molecules? Which chain makes up the peptide binding cleft in
MHC class II molecules?
An MHC class I molecule presents both intracellular antigens (e.g., viral antigen in cytoplasm) and
extracellular antigens (via cross-presentation). The loading site is endoplasmic reticulum (ER). -
correct answer-MHC class I molecule presents which type of antigens and where does the antigen-
MHC class I loading happen?
The MHC class II locus. They are involved in peptide processing for MHC class I however. - correct
answer-In which chromosomal region are the TAP proteins located?
,16 June 2026
The MHC class II molecule presents extracellular antigens (e.g., antigens from phagocytosed
bacteria). The loading site is phagolysosome. - correct answer-MHC class II molecule presents which
type of antigen? Where does the antigen-MHC class II loading happen?
IL-10 and TGFβ - correct answer-Which cytokines are important for Tregs?
TCR, MHC molecules, CD4, CD8, CD19, B7-1, B7-2, Fc receptors, KIR, and VCAM-1 - correct answer-
What molecules belong to the Ig superfamily?
Junctional diversity; TdT enzyme is important in this process. - correct answer-Which somatic
recombination process introduces the greatest diversity in immune receptors and which enzyme is
important in this process?
The FcRn receptor binds to IgG and allows it to be endocytosed. It protects it from the lysosome and
instead recycles it to the cell surface. This accounts for the long half-life of IgG in humans. This is also
the mechanism by which IgG is transported across the placenta and fetal intestine. IgG3 has the
shortest half-life because it poorly binds to FcRn. - correct answer-What is the role of the FcRn
receptor?
X-linked lymphoproliferative syndrome (XLP) - correct answer-Mutation in SAP causes which
disease?
Cyclosporine binds to cyclophilin, which are proteins also called immunophilins. The drug-protein
complex inhibits calcineurin and therefore NFAT translocation to the nucleus. - correct answer-
Immunosuppressant cyclosporine binds to which molecule in T-cell signaling pathway?
CD21, CD19, and CD81 - correct answer-What CD molecules are in the BCR coreceptor?
CXCR4 - correct answer-Which chemokine receptor is associated with WHIM (warts,
hypogammaglobulinemia, infections, amd myelokathexis) syndrome?
α4β7 - correct answer-Which integrin molecule is important for gut homing by binding to MAdCAM?
4-10 days - correct answer-Upon first exposure to a medication, when might a patient develop
symptoms of serum sickness?
,16 June 2026
IL-4 Rα, which is targeted by dupilumab - correct answer-Which component is shared by IL-4 and IL-
13 receptors?
IFNγ receptor deficiency results in susceptibility to Mycobacterium tuberculosis and other
intracellular bacteria. - correct answer-What is the result of IFNγ receptor deficiency?
IL-1β - correct answer-What interleukin is excessively produced in cryopyrinopathies?
Lipopolysaccharide responsive beige-like anchor protein (LRBA) deficiency - correct answer-What
disease presents with early onset hypogammaglobulinemia with autoimmunity and immune
dysregulation?
It maintains intracellular stores of CTLA4, which can stop T-cell activation. - correct answer-What is
the function of LRBA?
Properidin - correct answer-Which complement deficiency is inherited as X-linked?
CD 59 and S protein - correct answer-What two molecules inhibit MAC formation?
CD 55 and CD 59 - correct answer-Which complement receptor is implicated in PNH (paroxysmal
nocturnal hemoglobinuria)?
Adipose tissue - correct answer-What is the main source of Factor D?
HUVS (hypocomplementemic urticarial vasculitis) - correct answer-Anti-C1q antibody is found in
which disease process?
Factor XII - correct answer-Contact activation pathway is initiated by which factor?
B-2 receptor - correct answer-Bradykinin acts on what receptor on endothelial cells?
IgG and IgM - correct answer-What are the primary immunoglobulins involved with type II
hypersensitivity?
, 16 June 2026
Classical pathway - correct answer-IgG and IgM activate which complement pathway?
Both are type III hypersensitivity reactions; however, serum sickness is systemic and arthus reaction
is local - correct answer-How are serum sickness and arthus reaction similar and different?
Innate immunity and adaptive immunity - correct answer-Complement activation is involved with
what types of immunity?
PAMPS - correct answer-How do receptors of the innate immune system recognize microorganisms?
NODs - correct answer-What receptor is involved with the inflammasome?
TLR 3 - correct answer-Which TLR does not signal through MyD88?
TLR 4 - correct answer-Which TLR can signal through both MyD88 dependent and independent
pathways?
TLR 3, 7, 8, and 9 - correct answer-Which TLRs are present in the intracellular compartment and
implicated in HSV1 encephalitis?
PAMPs are conserved microbial sequences from microorganisms whereas DAMPs are endogenous
molecules derived from damaged or dying cells. - correct answer-How do PAMPS differ from
DAMPs?
TLR 4 - correct answer-Which TLR binds lipopolysaccharide (LPS) on gram-negative bacteria?
IL-6, TGFβ, IL-1, IL-21, and IL-23 - correct answer-Which cytokines induce development of Th17 cells?
TdT - correct answer-Which enzyme is responsible for adding nucleotides during junctional diversity?
Pre B cell - correct answer-At which stage does signaling through the pre-B-cell receptor occur?
ACAAI Review for the Allergy & Immunology Boards
PREP EXAM 2026/2027 LATEST EXAM TESTBANK UNDER NEW
GUIDELINE 450 QUESTIONS AND CORRECT ANSWERS PERFECT
TO PASS 2026 ACAAI TEST EXAM
Small-molecule antigen requires covalent linkage to a larger carrier to stimulate adaptive immune
response. The process is achieved in collaboration between hapten-specific B cells and carrier-
specific T cells. This is the basis of developing conjugated vaccines. - correct answer-What is the
hapten-carrier effect?
SEB and SEC from Staphylococcus aureus cause food poisoning. TSST from Staphylococcus aureus
and SPE-C from Streptococus pyogenes cause toxic shock syndrome. - correct answer-What are the
common superantigens and related diseases?
Natural killer T (NKT) cells recognize lipid antigens, and the CD1 molecule is involved. - correct
answer-Which type of T cell recognizes lipid antigens and what molecule is involved?
Protein antigens are T-cell dependent. Polysaccharide, nucleic acid, and lipids are T-cell
independent. - correct answer-Which antigens are T-cell dependent and which are T-cell
independent?
On the MHC class I molecule, α3 is the binding site for CD8. On the MHC class II molecule, β2 is the
binding site for CD4 - correct answer-What is the binding site for CD4 on the MHC class I molecule?
What is the binding site for CD8 on the MHC class II molecule?
On the MHC Class I molecule, α1 and α2 make up the peptide binding cleft. On the MHC class II
molecule, α1 and β1 make up the peptide binding cleft. - correct answer-Which chain makes up the
peptide binding cleft in MHC class I molecules? Which chain makes up the peptide binding cleft in
MHC class II molecules?
An MHC class I molecule presents both intracellular antigens (e.g., viral antigen in cytoplasm) and
extracellular antigens (via cross-presentation). The loading site is endoplasmic reticulum (ER). -
correct answer-MHC class I molecule presents which type of antigens and where does the antigen-
MHC class I loading happen?
The MHC class II locus. They are involved in peptide processing for MHC class I however. - correct
answer-In which chromosomal region are the TAP proteins located?
,16 June 2026
The MHC class II molecule presents extracellular antigens (e.g., antigens from phagocytosed
bacteria). The loading site is phagolysosome. - correct answer-MHC class II molecule presents which
type of antigen? Where does the antigen-MHC class II loading happen?
IL-10 and TGFβ - correct answer-Which cytokines are important for Tregs?
TCR, MHC molecules, CD4, CD8, CD19, B7-1, B7-2, Fc receptors, KIR, and VCAM-1 - correct answer-
What molecules belong to the Ig superfamily?
Junctional diversity; TdT enzyme is important in this process. - correct answer-Which somatic
recombination process introduces the greatest diversity in immune receptors and which enzyme is
important in this process?
The FcRn receptor binds to IgG and allows it to be endocytosed. It protects it from the lysosome and
instead recycles it to the cell surface. This accounts for the long half-life of IgG in humans. This is also
the mechanism by which IgG is transported across the placenta and fetal intestine. IgG3 has the
shortest half-life because it poorly binds to FcRn. - correct answer-What is the role of the FcRn
receptor?
X-linked lymphoproliferative syndrome (XLP) - correct answer-Mutation in SAP causes which
disease?
Cyclosporine binds to cyclophilin, which are proteins also called immunophilins. The drug-protein
complex inhibits calcineurin and therefore NFAT translocation to the nucleus. - correct answer-
Immunosuppressant cyclosporine binds to which molecule in T-cell signaling pathway?
CD21, CD19, and CD81 - correct answer-What CD molecules are in the BCR coreceptor?
CXCR4 - correct answer-Which chemokine receptor is associated with WHIM (warts,
hypogammaglobulinemia, infections, amd myelokathexis) syndrome?
α4β7 - correct answer-Which integrin molecule is important for gut homing by binding to MAdCAM?
4-10 days - correct answer-Upon first exposure to a medication, when might a patient develop
symptoms of serum sickness?
,16 June 2026
IL-4 Rα, which is targeted by dupilumab - correct answer-Which component is shared by IL-4 and IL-
13 receptors?
IFNγ receptor deficiency results in susceptibility to Mycobacterium tuberculosis and other
intracellular bacteria. - correct answer-What is the result of IFNγ receptor deficiency?
IL-1β - correct answer-What interleukin is excessively produced in cryopyrinopathies?
Lipopolysaccharide responsive beige-like anchor protein (LRBA) deficiency - correct answer-What
disease presents with early onset hypogammaglobulinemia with autoimmunity and immune
dysregulation?
It maintains intracellular stores of CTLA4, which can stop T-cell activation. - correct answer-What is
the function of LRBA?
Properidin - correct answer-Which complement deficiency is inherited as X-linked?
CD 59 and S protein - correct answer-What two molecules inhibit MAC formation?
CD 55 and CD 59 - correct answer-Which complement receptor is implicated in PNH (paroxysmal
nocturnal hemoglobinuria)?
Adipose tissue - correct answer-What is the main source of Factor D?
HUVS (hypocomplementemic urticarial vasculitis) - correct answer-Anti-C1q antibody is found in
which disease process?
Factor XII - correct answer-Contact activation pathway is initiated by which factor?
B-2 receptor - correct answer-Bradykinin acts on what receptor on endothelial cells?
IgG and IgM - correct answer-What are the primary immunoglobulins involved with type II
hypersensitivity?
, 16 June 2026
Classical pathway - correct answer-IgG and IgM activate which complement pathway?
Both are type III hypersensitivity reactions; however, serum sickness is systemic and arthus reaction
is local - correct answer-How are serum sickness and arthus reaction similar and different?
Innate immunity and adaptive immunity - correct answer-Complement activation is involved with
what types of immunity?
PAMPS - correct answer-How do receptors of the innate immune system recognize microorganisms?
NODs - correct answer-What receptor is involved with the inflammasome?
TLR 3 - correct answer-Which TLR does not signal through MyD88?
TLR 4 - correct answer-Which TLR can signal through both MyD88 dependent and independent
pathways?
TLR 3, 7, 8, and 9 - correct answer-Which TLRs are present in the intracellular compartment and
implicated in HSV1 encephalitis?
PAMPs are conserved microbial sequences from microorganisms whereas DAMPs are endogenous
molecules derived from damaged or dying cells. - correct answer-How do PAMPS differ from
DAMPs?
TLR 4 - correct answer-Which TLR binds lipopolysaccharide (LPS) on gram-negative bacteria?
IL-6, TGFβ, IL-1, IL-21, and IL-23 - correct answer-Which cytokines induce development of Th17 cells?
TdT - correct answer-Which enzyme is responsible for adding nucleotides during junctional diversity?
Pre B cell - correct answer-At which stage does signaling through the pre-B-cell receptor occur?
