MICB 212 MIDTERM 2 EXAMINATION TEST
FINAL PAPER FULL SOLUTION 2026 GRADED
A+.
⩥ Humoral immunity. Answer: - includes antibodies and the
cells/pathways they influence (phagocytosis, neutralization,
complement)
- can be passive by transferring antibody containing serum to another
individual
⩥ What is an extracellular bacterial infection?. Answer: - infections
where bacteria do not invade the cells of the host
- antibodies would be most appropriate form of an adaptive immune
response
⩥ Describe the innate immune response to an extracellular bacterial
infection. Answer: Innate immune response:
- at site of tissue damage, resident mast cells release histamine
- complement proteins enter tissue and kill many types of bacteria via
alternate pathway
- resident macrophages recognize PAMPs with their PRRs and
phagocytose bacteria + produce alarm cytokines (TNF-alpha, IL-1,
IL-6)
- resident macrophages also release substances to recruit neutrophiles
and monocytes to site of infection
,⩥ Describe the role of dendritic cells in the response to an
extracellular bacterial infection. Answer: - immature dendritic cells in
the skin engulf bacteria, process is and display it on MHC class II
proteins
- travel to lymph node to present the peptide fragments to a T helper
cell
- activate CD4 T helper cells
- produce IL-12 + IL-18
⩥ Describe T helper cell effector functions during an extracellular
bacterial infection. Answer: - produce IL-2 which supports clonal
proliferation
- produce IFN-gamma in response to IL-12 and IL-18 which causes
IgG class switch in activated B cells
⩥ Describe cytotoxic T cell effector functions during an extracellular
bacterial infection. Answer: N/a
⩥ Describe B cell (antibody) effector functions during an extracellular
bacterial infection. Answer: - antibodies are carried through the blood
to the site of infection
- antibodies are IgM at first, then class switch to IgG which can
opsonize and form the membrane attack complex (MAC)
,⩥ What is an intracellular bacterial infection?. Answer: - where
intracellular bacteria invade and live inside host cells (ie.
macrophages)
- bacteria are able to shut down the innate immune responses and
reproduce inside the host cell
- for bacteria that replicate inside macrophages, antibodies would not
be useful -> cell-mediate immune responses are needed (use T cells
and macrophages to kill the pathogen)
⩥ Describe the innate immune response to an intracellular bacterial
infection. Answer: - at site of tissue damage, resident mast cells
release histamine
- complement proteins enter tissue and kill many types of bacteria via
alternate pathway
- resident macrophages recognize PAMPs with their PRRs and
phagocytose bacteria + produce alarm cytokines (TNF-alpha, IL-1,
IL-6)
- resident macrophages also release substances to recruit neutrophiles
and monocytes to site of infection
*when macrophage engulfs the bacteria, the bacteria takes over the
cell
- if the macrophage receives special instruction from a T helper cell, it
would know that additional genes are needed to transcribe toxic
compounds to kill bacteria
, ⩥ Describe the role of dendritic cells in response to an intracellular
bacterial infection. Answer: - immature dendritic cells phagocytose
bacteria at site of infection
- travel to lymph node and present peptide on MHC class II proteins
to activate T helper cells
- instructs T helper cells to travel to site of infected macrophage -> T
helper cell secretes IFN-gamma at site of infection
⩥ Describe how macrophages are super activated. Answer: - can be
super activated by 2 signals:
T helper cells secrete IFN-gamma and other cytokines (signal 1) and
binding of CD40L on T cell and CD40 on macrophage (signal 2)
⩥ Consequences of super activating a macrophage. Answer: -
macrophages become more effective at fusing lysosomes with
phagosomes
- macrophages increase production of antimicrobial properties (ie.
nitric oxide, oxygen radicals and proteases) *sometimes these
compounds leak out of the macrophage and damage the healthy cells
and tissues of the host
- lots of local inflammation
⩥ Describe the CD8 T cell effector functions in an intracellular
bacterial infection. Answer: ?
FINAL PAPER FULL SOLUTION 2026 GRADED
A+.
⩥ Humoral immunity. Answer: - includes antibodies and the
cells/pathways they influence (phagocytosis, neutralization,
complement)
- can be passive by transferring antibody containing serum to another
individual
⩥ What is an extracellular bacterial infection?. Answer: - infections
where bacteria do not invade the cells of the host
- antibodies would be most appropriate form of an adaptive immune
response
⩥ Describe the innate immune response to an extracellular bacterial
infection. Answer: Innate immune response:
- at site of tissue damage, resident mast cells release histamine
- complement proteins enter tissue and kill many types of bacteria via
alternate pathway
- resident macrophages recognize PAMPs with their PRRs and
phagocytose bacteria + produce alarm cytokines (TNF-alpha, IL-1,
IL-6)
- resident macrophages also release substances to recruit neutrophiles
and monocytes to site of infection
,⩥ Describe the role of dendritic cells in the response to an
extracellular bacterial infection. Answer: - immature dendritic cells in
the skin engulf bacteria, process is and display it on MHC class II
proteins
- travel to lymph node to present the peptide fragments to a T helper
cell
- activate CD4 T helper cells
- produce IL-12 + IL-18
⩥ Describe T helper cell effector functions during an extracellular
bacterial infection. Answer: - produce IL-2 which supports clonal
proliferation
- produce IFN-gamma in response to IL-12 and IL-18 which causes
IgG class switch in activated B cells
⩥ Describe cytotoxic T cell effector functions during an extracellular
bacterial infection. Answer: N/a
⩥ Describe B cell (antibody) effector functions during an extracellular
bacterial infection. Answer: - antibodies are carried through the blood
to the site of infection
- antibodies are IgM at first, then class switch to IgG which can
opsonize and form the membrane attack complex (MAC)
,⩥ What is an intracellular bacterial infection?. Answer: - where
intracellular bacteria invade and live inside host cells (ie.
macrophages)
- bacteria are able to shut down the innate immune responses and
reproduce inside the host cell
- for bacteria that replicate inside macrophages, antibodies would not
be useful -> cell-mediate immune responses are needed (use T cells
and macrophages to kill the pathogen)
⩥ Describe the innate immune response to an intracellular bacterial
infection. Answer: - at site of tissue damage, resident mast cells
release histamine
- complement proteins enter tissue and kill many types of bacteria via
alternate pathway
- resident macrophages recognize PAMPs with their PRRs and
phagocytose bacteria + produce alarm cytokines (TNF-alpha, IL-1,
IL-6)
- resident macrophages also release substances to recruit neutrophiles
and monocytes to site of infection
*when macrophage engulfs the bacteria, the bacteria takes over the
cell
- if the macrophage receives special instruction from a T helper cell, it
would know that additional genes are needed to transcribe toxic
compounds to kill bacteria
, ⩥ Describe the role of dendritic cells in response to an intracellular
bacterial infection. Answer: - immature dendritic cells phagocytose
bacteria at site of infection
- travel to lymph node and present peptide on MHC class II proteins
to activate T helper cells
- instructs T helper cells to travel to site of infected macrophage -> T
helper cell secretes IFN-gamma at site of infection
⩥ Describe how macrophages are super activated. Answer: - can be
super activated by 2 signals:
T helper cells secrete IFN-gamma and other cytokines (signal 1) and
binding of CD40L on T cell and CD40 on macrophage (signal 2)
⩥ Consequences of super activating a macrophage. Answer: -
macrophages become more effective at fusing lysosomes with
phagosomes
- macrophages increase production of antimicrobial properties (ie.
nitric oxide, oxygen radicals and proteases) *sometimes these
compounds leak out of the macrophage and damage the healthy cells
and tissues of the host
- lots of local inflammation
⩥ Describe the CD8 T cell effector functions in an intracellular
bacterial infection. Answer: ?
