Innate Immunity
These two mechanisms are used by mucous membranes to trap and remove pathogens.
mucus and cilia
These are the two main branches of the adaptive immune system, and the primary lymphocytes responsible for each.
humoral: B-cells
cellular: T-cells
This process begins when an antigen binds to a B cell receptor and results in the production of plasma and memory cells.
contal selection
This molecule presents exogenous antigens to CD4 T cells, triggering their activation.
MHCII
This antibody class is responsible for triggering allergic reactions by binding to mast cells and basophils.
IgE
Name the steps of phagocytosis.
Adhesion
Engulfment
Fusion
Digestion enzyme breakdown
Exocytosis
This term describes a molecule that can trigger an immune response by stimulating lymphocytes and binding immune cells.
complete antigen
Identify the differences between active and passive immunity.
active immunity: body makes antibodies, long-term protection, takes time to develop, natural = getting sick + recovering, artificial = vaccination
passive immunity: antibodies are given to you (usually via mother IgG), short-term protection, immediate effect, natural = mothers milk/placenta, artificial = antibody injection
Before a T cell can become fully activated, it must receive two signals: one from antigen recognition and one from this process.
costimulation
List the sequence of events during a secondary exposure to an allergen.
1. more of allergen invades body
2. antibody-antigen binding triggers histamine release
3. Blood vessels dilate and smooth muscle contracts causing asthma
This is the sequence of events in phagocyte mobilization in response to infection.
Leukocytosis
Margination
Diapedesis
Chemotaxis
These proteins are self-antigens found on all body cells that present foreign or self peptides to T cells.
MHC (major histocompatibility complex)
Name and describe each antibody function.
Neutralization: blocks harmful sites
Agglutination: clumps cells
Precipitation: clumps soluble antigens
Complement activation: triggers lysis via MAC
This cytokine is secreted by activated helper T cells and is required for the costimulation of CD4, CD8, and B cells.
interleukin-2 (IL-2)
The cell type most often invaded by HIV is a
CD-4 cell
Name all six internal defenses of innate immunity and briefly describe their roles.
Phagocytosis: ingest + digest pathogens
Phagocyte mobilization: WBC recruitment
Inflammation: traps infection, promotes healing
Interferon: blocks viral replication
Complement activation: opsonization + lysis via MAC
Fever: increases metabolism, limits nutrients to bacteria
What are the two criteria that define a complete antigen, and how do they differ from self antigens?
Immunogenicity: ability to stimulate lymphocyte proliferation
Reactivity: ability to bind immune components
Self antigens (like MHC) do not trigger immune attack under normal conditions but help present other antigens
Which antibodies activate complement?
IgG and IgM
Cytotoxic T cells destroy infected or abnormal cells using these two molecules, which cause lysis and apoptosis.
perforin and granzymes
Which of the following is the function of the complement membrane attack complex (MAC)?
A. Stimulates antibody production
B. Forms pores in target cell membranes
C. Neutralizes toxins
D. Promotes phagocytosis by releasing cytokines
B. Forms pores in target cell membranes
Explain how interferons and complement activation differ in their antiviral vs. antibacterial roles, including the specific mechanisms each uses.
Interferons: released by virus-infected cells and signal nearby cells to produce antiviral proteins, preventing viral replication
Complement activation: enhances immune responses mainly against bacteria via
Inflammation: release of histamines
MAC: leads to cell lysis via holes in membrane
Opsonization: tags foreign pathogens for elimination by phagocytes
Compare how B cells and T cells recognize antigens and what happens after each is activated.
B-cells
-bind free antigens
-costimulation: IL-2
-proliferation + cloning results in plasma cells (effector) and memory cells
-plasma cells secrete antibodies for neutralization, agglutination, precipitation, and complement activation
T-cells
-bind processed antigens presented via MHC
-require costimulation
-differentiate into helper (CD4) or cytotoxic (CD8) T cells plus memory cells
List all five classes of antibodies and match each with one primary function or characteristic.
IgM- primary responder, strong agglutination
IgA- found in secretions, mucosal immunity
IgD- binds to B-cells
IgG- most abundant, crosses placenta
IgE- involved in allergic and parasitic responses
Compare the activation processes of CD4 and CD8 T cells, including the type of antigen, MHC class, and cytokine costimulation involved.
CD4 T cells bind exogenous antigens on MHC II and require IL-1 and IL-2 for costimulation
CD8 T cells bind endogenous antigens on MHC I and require IL-2 from CD4 helper cells
Both undergo clonal expansion into effector and memory T cells
What process ensures that developing lymphocytes do not mount immune responses against the body’s own cells?
A. Clonal selection
B. Self-tolerance
C. Chemotaxis
D. Agglutination
B. Self-tolerance