review concepts

A field studies how a host reacts when a foreign substance enters the body. Which field is this?

Immunology or serology.

What does the lecture call a foreign substance that causes the body to mount an immune response?

An antigen (Ag).

What does immunity mean in the introductory lecture?

The person is resistant to infection.

A person was deliberately exposed to smallpox lesions to try to create protection. What historical practice is this?

Variolation.

How did Edward Jenner use cross-immunity between cowpox and smallpox?

Cowpox material was injected to provide immunity to smallpox.

Which scientist is linked to attenuated vaccines in the lecture?

Louis Pasteur.

How does the lecture describe attenuation?

Infectious material is heated, aged, or chemically changed, then injected while still protecting from disease.

Scavenger cells attack an invading disease. Is this cellular or humoral immunity?

Cellular immunity.

Specific antibodies in blood protect against an invader. Is this cellular or humoral immunity?

Humoral immunity.

Why are acute-phase reactants different from antibodies?

They increase during attack or inflammation but are not specific for one disease.

A small substance can bind immune products but cannot trigger a response unless attached to a carrier. How does it differ from a complete antigen?

It is a hapten or incomplete antigen; a complete antigen can trigger the immune response by itself.

How does an opsonin increase phagocytosis?

It coats the foreign antigen so the body recognizes it as an attacker and phagocytes can take it up more easily.

A defense is present from birth, needs no prior exposure, and is nonspecific. Which immunity is it?

Natural or innate immunity.

Resistance develops after a pathogen has already made the body sick. Which immunity is described?

Acquired immunity.

How do skin oils and sweat support external innate defense?

Lactic acid in sweat and fatty acids in oil produce about pH 5.6.

Which external defenses act in the respiratory system, tears, and saliva?

Respiratory cilia and lysozyme enzymes in tears and saliva.

Why can antibiotics be followed by a Candida albicans yeast infection?

Loss of normal flora leaves space for foreign invaders to grow.

Which two flow or acidity defenses are emphasized?

Urine flow flushes the urinary tract; stomach acid is about pH 1.

What microbial feature is given as an example recognized by internal innate defense?

Mannose on bacteria.

A high CRP accompanies inflammation and should fall with treatment. What type of protein is CRP?

An acute-phase reactant.

Which acute-phase reactant is especially associated with heart problems such as MI?

High-sensitivity CRP (hsCRP).

Match the acute-phase reactant to its job: binds free hemoglobin and protects the kidney.

Haptoglobin.

Match the acute-phase reactant to its job: inhibits elastase; low levels can cause emphysema.

Alpha1-antitrypsin.

What does fibrinogen do in the lecture?

Forms a fibrin clot to seal a wound.

Which acute-phase protein binds copper?

Ceruloplasmin.

A segmented leukocyte leaves a vessel wall to enter tissue. What movement is occurring?

Diapedesis.

What directs segmented neutrophils to migrate in a particular direction?

Chemotaxins.

Which leukocyte has large red-orange granules, a usually bilobed nucleus, and increases in allergy and parasites?

Eosinophil.

How do eosinophils counter immediate hypersensitivity?

They neutralize products such as histamine from basophils and mast cells.

Which circulating leukocyte has deep blue-purple granules containing histamine, eosinophil chemotactic factor A, and some heparin?

Basophil.

Which long-lived tissue cell resembles a basophil, binds IgE, and functions in hypersensitivity?

Mast cell.

A circulating cell has a folded nucleus and becomes a macrophage after entering tissue. Which cell is it?

Monocyte.

Match each macrophage name with its site: alveolar, Kupffer, microglial, histiocyte.

Lung, liver, brain, and tissue, respectively.

Which cell with long extensions phagocytizes foreign antigen and presents it to helper T cells?

Dendritic cell.

Which cells are said to carry toll-like receptors in the lecture?

Monocytes, macrophages, and segmented neutrophils.

Put phagocytosis in lecture order.

Contact and opsonization; phagosome formation with oxidative burst; phagolysosome formation and killing; digestion and excretion.

What happens during the respiratory or oxidative burst?

Oxygen consumption increases as pseudopods close around the invader and killing products form.

Which enzyme acts on superoxide to help form hydrogen peroxide?

Superoxide dismutase.

Which enzyme helps form bleach-like hypochlorite ions?

Myeloperoxidase.

The body recognizes its own tissue antigens as good but treats what kind of antigen as a threat?

A foreign antigen.

What four traits make an effective immunogen or complete antigen?

Macromolecular size, chemical complexity, foreignness, and ability to be processed and presented with MHC.

What molecular-weight threshold is given for a more potent immunogen?

10,000 gram molecular weight or more.

How does increasing chemical complexity affect antigen potency?

Greater complexity produces a stronger reaction; proteins and polysaccharides are emphasized.

What does the lecture call blood-group antigens chemically?

Carbohydrates called glycolipids.

How does species distance affect foreignness and immune reaction?

The farther the antigen is from the host species, the greater the reaction.

Why must an immunogen be processable?

MHC takes smaller antigen pieces and presents them to T lymphocytes, which then make cytokines.

A small determinant site on an antigen binds antibody or a lymphocyte receptor. What is it?

An epitope.

Which B-cell structure can bind an epitope directly?

Surface antibody on the B cell.

Which T-cell types recognize foreign antigen presented with MHC?

CD4-positive and CD8-positive T cells.

Why can a hapten not create an immune response by itself?

It is too small and lacks a complex structure.

What allows a hapten to stimulate an immune response?

Attachment to a larger carrier molecule.

Which example of a hapten is given?

Poison ivy.

A patient with Epstein-Barr infectious mononucleosis has antibody that reacts with sheep RBCs. What type is it?

Heterophile antibody.

How does an adjuvant change a vaccine response?

It enhances the response so more antibody is made.

Which approved adjuvant example and vaccine are named?

Aluminum salts; hepatitis B vaccine.

What does MHC stand for?

Major Histocompatibility Complex.

How are MHC and HLA related?

MHC genes control expression of HLA antigens; HLA is part of MHC.

Where are Class I MHC molecules found, and which T cells receive their antigen?

On nucleated cells; they present to CD8-positive cytotoxic T lymphocytes.

What types of intracellular antigen does Class I surveillance watch for?

Viral, tumor, and parasitic antigens within cells.

Where are the Class I MHC genes located?

On the short arm of chromosome 6 at HLA-A, HLA-B, and HLA-C loci.

Which term means a specific location of a gene or DNA sequence on a chromosome?

A locus.

What do the lecture’s non-cell-surface MHC-region genes code for?

Complement proteins and cytokines such as tumor necrosis factor.

Why are Class I and II MHC antigens clinically important?

Both can contribute to graft rejection and play roles in autoimmune disease.

What shared job do Class I and II MHC molecules perform?

Bind foreign peptides, transport them to the plasma membrane, and present them to T cells.

What are alleles?

Different forms of genes at each locus.

A person expresses MHC alleles inherited from both parents. What inheritance pattern is this?

Codominant inheritance.

What does the lecture call the MHC package inherited from one parent?

A haplotype.

How does an immunogen differ from an antigen?

An immunogen produces an immune response; some antigens do not. All immunogens are antigens, but not all antigens are immunogens.

A substance may react with immune products but may not cause antibody formation. Is it complete or incomplete?

An incomplete antigen.

A substance causes antibody formation and reacts with sensitized cells. What is it?

A complete antigen, or immunogen.

How can foreign antigens enter and move through the body?

Through skin or GI and respiratory mucosa; the lymphatic system can carry them to lymph organs and circulation.

What are the two primary lymphoid organs?

Bone marrow and thymus.

Where do lymphocytes usually encounter foreign antigen?

In secondary lymphoid organs such as spleen, lymph nodes, appendix, tonsils, MALT, and Peyer’s patches.

How do spleen and lymph nodes differ as filters?

The spleen filters blood; lymph nodes filter lymph from tissues.

What does red pulp remove, and what does white pulp contain?

Red pulp destroys old RBCs; white pulp contains lymphocytes.

Where are T cells and B cells located in splenic white pulp?

T cells lie near central arterioles in PALS; B cells surround primary follicles.

What cells occupy a lymph-node primary follicle?

Resting B cells, a small number of T cells, and follicular dendritic cells.

What distinguishes a secondary lymph-node follicle from a primary follicle?

It contains antigen-stimulated B cells that can form plasma and memory cells.

What does MALT stand for?

Mucosa-associated lymph tissue.

Which secondary lymphoid tissues protect the GI tract and oral/pharyngeal cavities?

Peyer’s patches protect the GI tract; tonsils protect oral and pharyngeal cavities.

Why can lymphadenopathy occur after foreign-antigen contact?

Lymphocytes stop traveling and try to immobilize the antigen, enlarging nodes.

Describe the typical lymphocyte appearance and size.

Large round dense nucleus, small amount of cytoplasm, about 8-12 microns; T and B cells look alike.

Where do T, B, and NK cells originate?

From a common lymphoid precursor in bone marrow.

Which lymphocyte precursors go to the thymus, and which mature in bone marrow?

T-cell precursors go to thymus; B cells mature in bone marrow.

How does the thymus support T-cell maturation?

It supports maturation and exposes T cells to self antigens so they learn not to treat self as foreign.

How does the thymus change with age?

It atrophies.

What do cluster-of-differentiation antigens tell you about a lymphocyte?

They are surface marker proteins that identify the cell type and stage.

Which T-cell marker is linked to helper cells that make cytokines?

CD4.

Which T-cell marker is linked to cytotoxic suppressor cells?

CD8.

Which surface marker is found broadly on T cells and helps with T-cell adhesion or activation?

CD2.

Which surface marker is associated with the T-cell receptor and transmits its activation signal?

CD3.

Compare CD4 and CD8 recognition.

CD4 helper cells work with Class II MHC; CD8 cytotoxic cells work with Class I MHC.

Which CD markers are named on Pro-B cells?

CD19, CD43, CD45R, and CD24; TDT is also present.

Put B-cell maturation in lecture order.

Pro-B, Pre-B, immature B, mature B, activated B, then plasma or memory cell.

What immunoglobulin component forms first at the Pre-B stage?

The IgM heavy chain.

What antibody and markers appear on an immature B cell?

Complete surface IgM, plus CD21, CD40, and MHC Class II.

What happens to immature B cells that react with self antigen?

They die by apoptosis in bone marrow.

Which surface immunoglobulins identify mature or marginal-zone B cells?

IgM and IgD.

What event begins the antigen-dependent phase for a mature B cell?

Contact with foreign antigen, which activates the B cell.

Foreign antigen cross-links antibody on a B-cell surface. Which process is occurring?

Lymphocyte capping.