CH4 – Altered Immunity

A comprehensive set of vocabulary flashcards covering core concepts, cells, molecules, hypersensitivity types, and clinical disorders discussed in Chapter 4 – Altered Immunity.

Lymphatics

Network of organs and vessels (including spleen, lymph nodes, lymphoid tissue) essential for mounting an immune response.

Bone Marrow

Central lymphoid organ where all blood cells, including B lymphocytes, originate.

Thymus

Central lymphoid organ where T lymphocytes mature and differentiate.

Spleen

Peripheral lymphoid organ that filters blood and helps initiate immune responses to blood-borne antigens.

Lymph Nodes

Peripheral lymphoid structures that trap antigens and provide sites for immune cell activation and proliferation.

Innate Immunity

Nonspecific, immediate defense mechanism that includes epithelial barriers, neutrophils, macrophages, natural antibodies, and complement.

Adaptive Immunity

Antigen-specific defense involving B and T lymphocytes; develops immunologic memory.

Immunologic Memory

Ability of adaptive immunity to respond faster and more effectively to previously encountered antigens.

Lymphoid Progenitor Cell (Lymphoblast)

Bone-marrow-derived precursor that gives rise to B cells, T cells, and natural killer cells.

T Lymphocyte

Adaptive immune cell responsible for cell-mediated immunity; includes cytotoxic (CD8), helper (CD4), and regulatory subsets.

Cytotoxic T Cell (CD8)

T cell that directly kills virus-infected or cancerous cells via perforin and granzymes.

Helper T Cell (CD4)

T cell that orchestrates immune responses by activating B cells, cytotoxic T cells, and macrophages.

Regulatory T Cell

T cell that suppresses excessive immune responses, preventing autoimmunity.

B Lymphocyte

Adaptive immune cell that differentiates into plasma cells to secrete antibodies; key to humoral immunity.

Plasma Cell

Differentiated B cell specialized in large-scale antibody production.

Antibody (Immunoglobulin)

Y-shaped protein produced by B cells that binds specific antigens to neutralize or eliminate them.

Natural Killer (NK) Cell

Innate lymphocyte that destroys infected or malignant cells without prior sensitization.

Active Immunity

Immunity produced by one’s own body after exposure to antigen via infection or vaccination.

Passive Immunity

Temporary immunity acquired through transfer of antibodies (e.g., maternal IgG, IV immunoglobulin).

Humoral Immunity

Arm of adaptive immunity mediated by antibodies produced by B cells in body fluids (plasma).

Cell-Mediated Immunity

Adaptive immune response driven by T lymphocytes that target infected or abnormal cells.

IgA

Immunoglobulin found in saliva, tears, mucous, and breast milk; protects mucosal surfaces.

IgG

Most abundant antibody in blood; provides long-term immunity and is the only class that crosses the placenta.

IgM

First antibody produced in an initial immune response; activates complement and provides short-term defense.

IgE

Antibody that mediates allergic reactions and defense against parasites.

IgD

Least understood immunoglobulin; functions in activation and maturation of B cells.

Major Histocompatibility Complex (MHC)

Set of cell-surface proteins (HLA in humans) that present antigen fragments to T cells.

MHC Class I

MHC molecules present on all nucleated cells that display antigen to CD8 cytotoxic T cells.

MHC Class II

MHC molecules present on antigen-presenting cells that display antigen to CD4 helper T cells.

Host Defense Failure

Inability of the immune system to protect the host, leading to infection or disease.

Hypersensitivity

Excessive or inappropriate immune response causing tissue damage.

Autoimmunity

Immune reaction against self-antigens leading to tissue injury.

Alloimmunity

Immune response against antigens from members of the same species, as in graft rejection.

Antigenic Variation

Mechanism by which pathogens alter surface antigens to evade immune detection.

Viral Latency

Dormant state of viruses within host cells, allowing evasion of immune surveillance.

Immunodeficiency

State of reduced or absent immune function resulting in increased susceptibility to infection.

Type I Hypersensitivity

Immediate, IgE-mediated allergic reaction (e.g., anaphylaxis).

Type II Hypersensitivity

IgG or IgM-mediated cytotoxic reaction against cell surfaces (e.g., hemolytic anemia).

Type III Hypersensitivity

Immune complex deposition causing inflammation (e.g., systemic lupus erythematosus).

Type IV Hypersensitivity

Delayed, T-cell-mediated reaction (e.g., TB skin test, contact dermatitis).

Mast Cell

Granule-containing cell that releases histamine during allergic responses.

Histamine

Mediator released from mast cells causing vasodilation and increased capillary permeability.

Acquired Immunodeficiency Syndrome (AIDS)

Disease caused by HIV infection leading to progressive loss of CD4 T cells and immunosuppression.

CD4 T Helper Lymphocyte

Primary target of HIV; its depletion impairs both humoral and cell-mediated immunity.

Opportunistic Infection

Illness caused by organisms that rarely cause disease in immunocompetent hosts (e.g., Pneumocystis jirovecii pneumonia in AIDS).

Antiretroviral Therapy (ART)

Combination drug regimen that suppresses HIV replication, preserves immune function, and reduces morbidity.

Anaphylactic Reaction

Severe systemic Type I hypersensitivity response with vascular dilation and bronchoconstriction.

Angioedema

Rapid swelling of skin and mucosa seen in allergic reactions, including anaphylaxis.

Desensitization

Preventive therapy exposing a patient to increasing allergen doses to reduce hypersensitivity.

Systemic Lupus Erythematosus (SLE)

Chronic autoimmune, Type III hypersensitivity disease characterized by multi-system inflammation and autoantibodies.

Autoantibody

Antibody directed against the body’s own antigens, central to autoimmune diseases.

Rh Isoimmunization

Maternal immune response against fetal Rh-positive red blood cells, leading to hemolysis.

Anti-D Antibody

Maternal IgG targeting the Rh(D) antigen on fetal erythrocytes in Rh isoimmunization.

Hemolysis

Destruction of red blood cells releasing hemoglobin into circulation.

Hydrops Fetalis

Severe fetal edema resulting from anemia in Rh isoimmunization.

Kernicterus

Neurologic damage from bilirubin deposition in the brains of newborns with severe hemolysis.

Exchange Transfusion

Therapeutic replacement of an infant’s damaged red blood cells with healthy donor cells in Rh disease.