Introduction To Immunology: The Normal Immune Response

Front 1

List the principal cells and tissues of the immune system

Back 1

T lymphocytes: help for B cells and macrophages (CD4+ helper cells), killing of infected and tumor cells (CD8+ cytotoxic T lymphocytes)
B lymphocytes: Antibody production (B cells develop into plasma cells, which make antibodies)
Dendritic cells: Capture and display of foreign antigens (APCs)
Macrophages: Phagocytosis and killing of microbes; antigen capture and display (APCs); tissue repair
Neutrophils: Phagocytosis and killing of microbes

Tissues: epithelial and mucosal barriers for the skin, the respiratory tract and the GI tract that contact the environment directly, and the lymphoid tissues including bone marrow, spleen, tonsils, and lymph nodes.
Cells: develop from precursor cells in the bone marrow including lymphocytes, macrophages, and neutrophils.
Small protein molecules: serve as messenger molecules including cytokines and chemokines

Front 2

Summarize the main differences between innate and adaptive immunity

Back 2

Innate immunity is mediated by cells and proteins that are always present and ready to fight against microbes and are called into action immediately in response to infection. Response is not enhanced by prior exposure. Fixed specificity-pattern recognition. It also regulates the adaptive immune system. Major cells include: macrophages, neutrophils, and natural killer (NK) cells. Components include epithelial barriers of skin, GI tract, and respiratory tract. Circulating proteins (complement system) Key: they are present prior to exposure which results in rapid and immediate reaction. Utilizes stereotypical pattern recognition to identify non-self.

Adaptive immunity: normally silent and responds (adapts) to the presence of infectious microbes by becoming active, expanding, and generating potent mechanisms for neutralizing and eliminating the microbes. Antigen-specific (cognate) recognition; response tailored to specific antigen; response strengthened by repeated exposure; ability to develop tolerance (to food proteins for instance); amplifies and refines protection by the innate immune system. Major components include: lymphocytes (B and T cells) and their products (Ab or cytokines)

Front 3

Describe how lymphocytes respond to foreign antigens

Back 3

Recognition phase
Naïve lymphocytes recognize antigens presented by APCs through their surface antigen receptor
Each lymphocyte has a single antigenic specificity
B cells:
BRCs are membrane bound antibodies (Ig)
Recog variety of antigenic mlc types (macromlc, microbes, small chemicals, etc)
Most effective against extracellular microbes
T cells:
TRCs recog only small peptides as antigens
CD4+ T cells recog mlc displayed by APCs with MHC-II
CD8+ T cells recog mlc displayed by APCs with MHC-I
Most effective against intracellular microbes

Activation phase

Proliferation
Differentiation (effector cells, memory cells)

Effector phase – elimination of antigen

Decline (homeostasis)

Memory phase

Front 4

Describe how humoral and cell-mediated immune responses are induced by microbes and other foreign substances

Back 4

Humoral immunity refers to the production of antibodies by B cells. This type of immunity is effective against extracellular microbes which are accessible to antibodies.

Cell-mediated (or cellular) immunity is mediated by T cells, and is effective against intracellular microbes. Different types of T lymphocytes work in different ways to eliminate intracellular microbes: Helper T cells act on macrophages that have ingested microbes and activate the macrophages to kill these microbes. CTLs recognize microbes hiding in the cytoplasm of infected cells and kill the infected cells directly.

Front 5

Describe the principal functions of IgG, IgE and IgA antibody isotypes

Back 5

IgG – most prevalent: opsonization, complement activation, Antibody dependent cell cytotoxity, neonatal immunity
IgM: Complement Activation; B cell Ag receptor
IgA: mucosal immunity
IgE: ADCC – eosinophils; mast cell degranulation – hypersensitivity allergy response
IgD: B cell Ag receptor; basophil, mast cell activation

Front 6

Extra Information:

Back 6

Epitope: small portion of an antigenic molecule targeted in an immune response
Antigens: can be proteins, carbohydrates, nucleic acids, and lipids
T-dependent: protein
T-independent: non-peptide (carbohydrate)
T cells antigen receptor recognizes peptides
One lymphocyte clone=one epitope
Each lymphocyte produces a single species of antigen receptor
Naïve B cell encounters antigens and become activated with help from CD4 T cell
Opsonization: coats an antigen