PCB 4233 - SECTION 6 - ADAPTIVE IMMUNE RESPONSE EXAM QUESTIONS ANSWERED CORRECTLY
LATEST UPDATE 2026
Stages of the adaptive immune response - Answers Recognition (antigen detection), activation (clonal
expansion of B, T cells), effector phase (antigen removal and immune cells work), decline (immune cell
apoptosis), memory
Principle Facets of the Adaptive Immune Response - Answers Specificity (in response), diversity (large
numbers of microbes), memory (recall previous encounters to lead to faster + stronger responses in
future encounters), optimization (specialized attacks for distinct microbes), self-limiting (starting,
stopping attack of a new microbe), safe to self (tolerant)
Antigen - Answers Anything that elicits an immune response
Exceptions to antigen foreignness - Answers Autoimmune diseases (MS, RA)
Antigen molecular weight - Answers High (> 5kDa) or low (haptens; attached to large MW
compounds)
Outdated term for natural killer cells - Answers Null cells
B lymphocytes mature in - Answers Bone marrow
B lymphocytes circulate in - Answers Blood
B lymphocytes can settle in - Answers Lymphoid organs
After maturation and activation, some B lymphocytes become ____ that secrete large volumes of
______ - Answers Plasma cells, antibodies
T lymphocytes mature in - Answers Thymus
After maturation, naive T lymphocytes can do what three options? - Answers Remain in thymus
(though most migrate out), circulate in blood, reside in lymphoid tissue
Unlike B cells, for T cells, antigen must be presented by - Answers APC in the context of MHC
Activated T cells produce - Answers Cytokines
Signal reception types - Answers Cell surface receptor, water-soluble ligand, or membrane-soluble
ligand
Signal transduction process - Answers Ligand binding to receptor induces assembly of signaling
pathway components, generating second messenger that carries signal to cell interior;
phosphorylation/dephosphorylation cycles under control of the signaling pathway to
activate/deactivate pathway components; enzyme cascades amplify the signal
In addition to peptide and MHC, naive T cells require - Answers Interaction with other molecules on
the surface of APCs (co-stimulators)
Purpose of co-stimulators interacting with naive T cells - Answers Prevents T cell activation by
harmless molecules
CD4:CD8 ratio in peripheral blood - Answers 2:1
Major TCR - Answers alpha/beta
alpha beta T cells proportion in blood - Answers 90-99%
gamma beta T cells proportion in blood - Answers 1-10%
MHC restrictions for alpha/beta and gamma/delta T cells - Answers a/b: MHC class II and I; g/d: no
MHC restriction
No co-stimulation of naïve T cells - Answers Anergy
Antibody components - Answers Two light chains, two heavy chains connected by disulfide bonds and
consisting of variable (uppermost) and hypervariable (distinct, within uppermost) regions
Where is antibody activity found in the antibody? - Answers Light chains, top region
Where is biological activity/binding of complement found in the antibody? - Answers Heavy chains,
bottom region
CD4 (Th) cell subtypes - Answers TH1, TH2, TH17, T Follicular helpers
TH1 - Answers INF gamma, intracellular pathogens
TH2 - Answers IL-4, extracellular pathogens (bacteria)
TH17 - Answers IL-17, extracellular pathogens (fungi)
T Follicular Helpers - Answers Important in humoral immunity and B cell development in germinal
centers (lymphoid follicles)
CTLA4 competes with - Answers CD28
Cytokine signaling suppressors include - Answers Immunomodulatory cytokines (IL-10), PD-1 ligands,
Tregs
What happens in the absence of continued TCR stimulation? - Answers Apoptosis
LATEST UPDATE 2026
Stages of the adaptive immune response - Answers Recognition (antigen detection), activation (clonal
expansion of B, T cells), effector phase (antigen removal and immune cells work), decline (immune cell
apoptosis), memory
Principle Facets of the Adaptive Immune Response - Answers Specificity (in response), diversity (large
numbers of microbes), memory (recall previous encounters to lead to faster + stronger responses in
future encounters), optimization (specialized attacks for distinct microbes), self-limiting (starting,
stopping attack of a new microbe), safe to self (tolerant)
Antigen - Answers Anything that elicits an immune response
Exceptions to antigen foreignness - Answers Autoimmune diseases (MS, RA)
Antigen molecular weight - Answers High (> 5kDa) or low (haptens; attached to large MW
compounds)
Outdated term for natural killer cells - Answers Null cells
B lymphocytes mature in - Answers Bone marrow
B lymphocytes circulate in - Answers Blood
B lymphocytes can settle in - Answers Lymphoid organs
After maturation and activation, some B lymphocytes become ____ that secrete large volumes of
______ - Answers Plasma cells, antibodies
T lymphocytes mature in - Answers Thymus
After maturation, naive T lymphocytes can do what three options? - Answers Remain in thymus
(though most migrate out), circulate in blood, reside in lymphoid tissue
Unlike B cells, for T cells, antigen must be presented by - Answers APC in the context of MHC
Activated T cells produce - Answers Cytokines
Signal reception types - Answers Cell surface receptor, water-soluble ligand, or membrane-soluble
ligand
Signal transduction process - Answers Ligand binding to receptor induces assembly of signaling
pathway components, generating second messenger that carries signal to cell interior;
phosphorylation/dephosphorylation cycles under control of the signaling pathway to
activate/deactivate pathway components; enzyme cascades amplify the signal
In addition to peptide and MHC, naive T cells require - Answers Interaction with other molecules on
the surface of APCs (co-stimulators)
Purpose of co-stimulators interacting with naive T cells - Answers Prevents T cell activation by
harmless molecules
CD4:CD8 ratio in peripheral blood - Answers 2:1
Major TCR - Answers alpha/beta
alpha beta T cells proportion in blood - Answers 90-99%
gamma beta T cells proportion in blood - Answers 1-10%
MHC restrictions for alpha/beta and gamma/delta T cells - Answers a/b: MHC class II and I; g/d: no
MHC restriction
No co-stimulation of naïve T cells - Answers Anergy
Antibody components - Answers Two light chains, two heavy chains connected by disulfide bonds and
consisting of variable (uppermost) and hypervariable (distinct, within uppermost) regions
Where is antibody activity found in the antibody? - Answers Light chains, top region
Where is biological activity/binding of complement found in the antibody? - Answers Heavy chains,
bottom region
CD4 (Th) cell subtypes - Answers TH1, TH2, TH17, T Follicular helpers
TH1 - Answers INF gamma, intracellular pathogens
TH2 - Answers IL-4, extracellular pathogens (bacteria)
TH17 - Answers IL-17, extracellular pathogens (fungi)
T Follicular Helpers - Answers Important in humoral immunity and B cell development in germinal
centers (lymphoid follicles)
CTLA4 competes with - Answers CD28
Cytokine signaling suppressors include - Answers Immunomodulatory cytokines (IL-10), PD-1 ligands,
Tregs
What happens in the absence of continued TCR stimulation? - Answers Apoptosis
