Chapter 7 – Immunity: Key Vocabulary

Vocabulary flashcards summarizing essential terms and definitions from Chapter 7 on Immunity, covering immune components, antibody types, hypersensitivity, autoimmune diseases, immunodeficiency, and HIV/AIDS treatment.

Immunity

The body’s ability to resist or eliminate potentially harmful foreign materials or abnormal cells.

Nonspecific (innate) response

General defense mechanisms such as phagocytosis and inflammation that act against any pathogen.

Specific (adaptive) response

Immune reaction that targets a particular antigen through production of specific antibodies or sensitized cells.

Lymphoid structures

Anatomical sites (lymph nodes, spleen, tonsils, intestinal tissue) where immune cells reside and interact.

Bone marrow

Primary lymphoid tissue where all blood and immune cells originate.

Thymus

Organ where T lymphocytes mature and become immunocompetent.

Antigen

Any substance that is recognized as foreign (non-self) and provokes an immune response.

HLA proteins

Self-markers on cell membranes that allow the immune system to recognize body cells as ‘self’.

Macrophage

Large phagocytic cell that engulfs pathogens, presents antigens, and releases cytokines.

T lymphocyte (T cell)

White blood cell responsible for cell-mediated immunity; includes helper, cytotoxic, and memory subsets.

B lymphocyte (B cell)

White blood cell that differentiates into plasma cells to produce antibodies (humoral immunity).

Humoral immunity

Protection provided by antibodies circulating in body fluids.

Cell-mediated immunity (CMI)

Defense carried out by sensitized T cells that destroy infected or abnormal cells.

IgG

Most abundant immunoglobulin in blood; provides long-term protection and crosses placenta.

IgM

First antibody produced in an initial immune response; excellent at agglutination.

IgA

Immunoglobulin found in secretions such as saliva, tears, mucus, and colostrum.

IgE

Antibody involved in allergic reactions; triggers histamine release from mast cells.

IgD

Immunoglobulin located on B-cell surfaces; functions in B-cell activation.

Complement system

Cascade of serum proteins (C1–C9) that amplify immune reactions and lyse target cells when activated.

Histamine

Chemical mediator released from mast cells causing vasodilation and increased permeability during inflammation.

Cytokine

Small protein (e.g., interleukin) that acts as a messenger between immune cells.

Titer (titre)

Laboratory measurement of the concentration of specific antibodies in serum.

ELISA

Enzyme-linked immunosorbent assay used to detect antibodies (e.g., HIV) in patient serum.

MHC typing

Laboratory matching of HLA antigens before tissue or organ transplantation.

Primary immune response

Slow first reaction to an antigen; antibodies appear after 1–2 weeks.

Secondary immune response

Rapid, strong reaction on re-exposure to the same antigen due to memory cells.

Active natural immunity

Immunity acquired by natural exposure to a pathogen resulting in antibody production.

Active artificial immunity

Immunity achieved through vaccination with antigen to stimulate antibody formation.

Passive natural immunity

Temporary protection gained from maternal IgG crossing placenta or through breast milk.

Passive artificial immunity

Short-term protection via injection of preformed antibodies (antiserum).

Herd immunity

Community protection that occurs when high vaccination rates limit pathogen spread.

Emerging infectious disease

Newly identified disease appearing in a population for the first time.

Re-emerging disease

Previously controlled infection that returns due to factors like reduced vaccination.

Bioterrorism

Use of biological agents to deliberately harm civilian or military populations.

Hyperacute rejection

Immediate transplant rejection occurring minutes to hours after grafting.

Acute rejection

Transplant rejection developing days to weeks post-surgery.

Chronic rejection

Slow, progressive loss of graft function occurring months or years after transplant.

Immunosuppression

Deliberate reduction of immune activity to prevent transplant rejection or treat disease.

Cyclosporine

Common immunosuppressive drug that inhibits T-cell function.

Type I hypersensitivity

IgE-mediated allergic reaction involving mast-cell degranulation; may cause anaphylaxis.

Anaphylaxis

Severe systemic allergic reaction with hypotension, airway obstruction, and shock.

Epinephrine

Drug of choice for treating anaphylactic shock; reverses bronchoconstriction and vasodilation.

Type II cytotoxic hypersensitivity

IgG-mediated destruction of cells bearing antigen (e.g., incompatible blood transfusion).

Type III immune complex hypersensitivity

Deposition of antigen-antibody complexes in tissues leading to inflammation (e.g., glomerulonephritis).

Type IV cell-mediated hypersensitivity

Delayed reaction mediated by sensitized T cells (e.g., contact dermatitis, TB test).

Autoantibody

Antibody directed against self-antigens, leading to autoimmune disease.

Systemic Lupus Erythematosus (SLE)

Chronic autoimmune disease characterized by widespread inflammation and ‘butterfly’ facial rash.

Immunodeficiency

Partial or total loss of immune function, increasing susceptibility to infection and cancer.

Opportunistic infection

Infection by normally harmless organisms in individuals with weakened immunity.

Acquired Immunodeficiency Syndrome (AIDS)

Advanced stage of HIV infection marked by severe immunosuppression and opportunistic diseases.

Human Immunodeficiency Virus (HIV)

Retrovirus that targets and destroys CD4 helper T cells.

CD4 T cell

Helper lymphocyte crucial for coordinating immune responses; primary target of HIV.

Antiretroviral therapy (ART)

Combination drug treatment that inhibits various stages of HIV replication.

NNRTI

Non-nucleoside reverse transcriptase inhibitor; blocks HIV reverse transcriptase enzyme.

NRTI

Nucleoside reverse transcriptase inhibitor; mimics nucleotides to stop viral DNA synthesis.

Protease inhibitor (PI)

Drug that blocks HIV protease, preventing maturation of new virus particles.

Integrase strand transfer inhibitor (INSTI)

Medication that inhibits insertion of viral DNA into host genome.

CCR5 antagonist

Entry inhibitor that blocks HIV from binding to CCR5 co-receptors on host cells.

Fusion inhibitor

Antiretroviral that prevents HIV envelope from fusing with host cell membrane.

Kaposi sarcoma

Vascular cancer associated with AIDS, presenting as purple skin or mucosal lesions.

Pneumocystis carinii pneumonia

Common opportunistic lung infection in AIDS caused by Pneumocystis jirovecii.