This is the primary antibody produced in a primary immune response by B-cells
IgM

This molecule stabilizes interaction between CD4+ T cells and APCs
MHC class II

Antibody class that crosses the placenta
IgG

Presents endogenous antigens
MHC class I
These cells persist after infection and respond rapidly
Memory B and T cells
Process by which B cells improve antibody affinity.
bonus points for listing all possible combinations of VDJ recombination ;)
Somatic hypermutation
10^18 possible combinations
Cytokine that drives Th1 differentiation and its supporting Interferon
IL-12, IFN-gamma
Antibody involved in allergic responses
IgE

Cell type that is the most potent antigen-presenting cell
Dendritic cell

Location of long-lived plasma cells
Bone marrow
Structure within lymph nodes where B-cell maturation occurs
Germinal center

Key function of CD8+ T cells
Cytotoxic killing (perforin/granzyme)

Process where antibodies enhance phagocytosis
Opsonisation

Mechanism allowing extracellular antigens on MHC I
Cross-presentation
Antibody isotype predominating in secondary responses
IgG
Enzyme responsible for class switching and somatic hypermutation
Activation-induced cytidine deaminase (AID)
This checkpoint molecule downregulates T-cell activation
CTLA-4
Complement pathway triggered by antigen-antibody complexes
Classical pathway
Location where naive T cells encounter antigen
Lymph node (secondary lymphoid organs)

This cytokine supports memory T-cell survival.
IL-7
This receptor allows B cells to present antigen to T cells.
MHC class II
This co-receptor on T cells binds MHC class I molecules
CD8
This region of antibody binds Fc receptors of immune cells
Fc region
This professional antigen presenting cell is the most effective at activating naïve T cells.
dendritic cell

Explain why secondary immune responses are faster and more effective than primary responses
Pre-existing memory B/T cells
Faster activation (lower threshold)
Class-switched antibodies (IgG)
Higher affinity (somatic hypermutation)
More rapid clonal expansion