Immuno Test 1 Vocab

Antigen

Substance recognized by the immune system that does not always trigger a reaction.

Immunogen

A specific type of foreign antigen that always induces an active immune response.

Innate Immunity

Baseline natural immunity present at birth that lacks memory and reacts immediately.

Adaptive Immunity

Specific acquired immunity that requires prior antigen exposure and generates memory.

Hematopoietic Stem Cells (HSCs)

Pluripotent bone marrow stem cells that give rise to all white blood cells.

Common Myeloid Progenitor (CMP)

The stem cell branch that generates neutrophils, basophils, eosinophils, and monocytes.

Common Lymphoid Progenitor (CLP)

The stem cell branch that generates T cells, B cells, and Natural Killer cells.

Neutrophil (Seg / PMN)

Most abundant circulating WBC (50% to 70%) that handles enzyme-driven phagocytosis of bacteria.

Eosinophil

Granulocyte (1% to 4%) that kills large parasites by dumping granules and regulates mast cells.

Basophil

Circulating granulocyte (<1%) that induces and maintains allergic reactions via histamine release.

Mast Cell

Tissue-resident cell that causes allergic reactions and functions as an innate antigen-presenting cell.

Monocyte

Circulating white blood cell (4% to 10%) that migrates directly into host tissues to differentiate.

Macrophage

Tissue-resident cell derived from monocytes that performs phagocytosis and processes antigens for adaptive cells.

Dendritic Cell

The most effective Antigen-Presenting Cell (APC) that bridges innate and adaptive arms in lymph nodes.

Cluster of Differentiation (CD)

Surface markers used in lab environments to identify and type lymphocytes.

Bone Marrow

Primary lymphoid organ that serves as the HSC niche and the maturation site for B cells.

Thymus

Primary lymphoid organ where T cell progenitors migrate from bone marrow to mature.

Spleen

Largest secondary lymphoid organ that filters bloodborne antigens and recycles old red blood cells.

Red Pulp

Macrophage-rich region of the spleen dedicated to destroying old or damaged erythrocytes.

White Pulp

Region of the spleen containing the PALS (T cells) and follicles (B cells) to trap blood antigens.

Peri-Arteriolar Lymphoid Sheath (PALS)

Specific white pulp coat wrapping central arterioles where T cells congregate.

Lymph Node

Small secondary lymphoid organ tracking fluid ducts that traps tissue-derived antigens.

Paracortex

The specific inner zone of a lymph node where mature T cells localize.

Cortex Follicles

Outer regions of lymph nodes where B cells aggregate to await activation.

MALT

Mucosa-Associated Lymphoid Tissue protecting entry pathways including tonsils, appendix, and Peyer's patches.

SALT

Skin-Associated Lymphoid Tissue composed of intraepidermal T cells, monocytes, and patrolling dendritic tracks.

External Defense System

Anatomical, physical, and chemical barriers that prevent infectious agents from entering tissues.

Internal Defense System

Cellular responses and soluble blood serum factors that defend once barriers are breached.

Psoriasin

Continuous antibacterial protein found in skin secretions that actively kills microbes.

Lysozyme

Chemical enzyme in tears and saliva that specifically lyses Gram-positive bacterial cell walls.

Surfactant

Chemical substance on mucous membranes that binds microbes to accelerate surface clearance.

Pattern Recognition Receptors (PRRs)

Host surface or internal sensors that detect generic pathogen signatures.

PAMPs

Pathogen-Associated Molecular Patterns; unique structural designs found only on infectious microorganisms.

DAMPs

Damage-Associated Molecular Patterns; products released by stressed, injured, or dying host cells.

Toll-Like Receptors (TLRs)

Class of 10 human PRRs tracking cell surfaces and endosomes to trigger cytokines.

C-Type Lectin Receptors (CLRs)

External PRRs that specifically target fungal carbohydrates like mannan and beta-glucan.

RIG-1-Like Receptors (RLRs)

Internal PRRs that recognize intracellular viral RNA to produce Type I Interferons.

NOD-Like Receptors (NLRs)

Intracellular PRRs that bind bacterial peptidoglycans to protect against protozoans.

Acute-Phase Reactants

Nonspecific serum proteins that rapidly spike during tissue damage or active infection.

Opsonization

Biochemical process of coating an invader with tagging proteins to facilitate phagocytic gripping.

C-Reactive Protein (CRP)

Core acute-phase protein driving opsonization and activating the complement cascade.

Serum Amyloid A

Acute-phase serum component that actively recruits and activates monocytes and macrophages.

Alpha1-Antitrypsin

Serum protease inhibitor that limits localized neutrophil tissue damage.

Fibrinogen

Acute-phase protein driving blood clot formation to isolate infection sites.

Haptoglobin

Serum protein that binds free hemoglobin to starve pathogens of vital nutrients.

Ceruloplasmin

Serum reactant that binds copper and oxidizes iron supplies to restrict microbial growth.

Complement C3

Central serum factor mediating both surface opsonization and target cell lysis.

Chemokines

Cell-attracting chemical signals released by tissue cells to recruit circulating neutrophils.

Diapedesis

The active process where white blood cells squeeze through altered capillary walls into tissue.

Phagolysosome

The vacuole formed when a pathogen-containing phagosome fuses with an enzyme-filled lysosome.

Oxidative Burst

Oxygen-dependent killing pathway generating highly toxic reactive oxygen species via the HMP shunt.

Natural Killer (NK) Cells

Innate lymphoid actors (CD16+/CD56+) patrolling for missing host tags or virus-coated targets.

Perforin

Membrane-disrupting protein released by NK cells to punch functional holes in target membranes.

Granzyme

Toxic enzyme injected through perforin holes to force infected host cell apoptosis.

ADCC

Antibody-Dependent Cell-Mediated Cytotoxicity; NK cells binding directly to antibody-coated targets to induce death.

Route of Inoculation

The path an antigen takes to enter the host, heavily influencing the immune response choice.

Oral Tolerance

The evolutionary mechanism where oral tissues downregulate responses so the host ignores food antigens.

Linear Epitope

A short, single chain of sequential amino acids recognized by both T and B cells.

Conformational Epitope

A 3D folded chain bringing distant residues together; recognized exclusively by B cells.

Nonimmunogenic

Small, simple chemical substances incapable of provoking an immune reaction independently.

Hapten

A small nonimmunogenic particle that cannot trigger an immune response until bound to a carrier molecule.

Adjuvant

An irritant compound added to shots to trigger PRRs and attract extra immune cells.

Autoantigen

Native host self-antigens that normally fail to elicit any active immune clearing.

Alloantigen

Antigens belonging to other individuals of the same species such as blood types or transplant tissue.

Heteroantigen

Antigens originating from an entirely different species such as animal or plant markers versus humans.

Heterophile Antigen

Unrelated species antigens sharing near-identical shapes, causing accidental cross-reactive clumping.

Human Leukocyte Antigens (HLA)

Genetic term for human MHC proteins encoded as an inherited block on Chromosome 6.

Haplotype

A linked set of genetic loci on a single chromosome inherited together as a package group from one parent.

Polymorphic

Displaying thousands of structural variations due to a vast number of alternative alleles in the population.

Codominant

Expression pattern where maternal and paternal alleles are displayed simultaneously on host cell walls.

Beta-2 Microglobulin

Non-polymorphic structural chain required to fold and stabilize MHC Class I molecules.

Endogenous Antigen

Peptide pieces originating inside the host cell such as viral proteins presented on MHC Class I.

Exogenous Antigen

Foreign fragments engulfed from outside by an APC and presented on MHC Class II molecules.

HLA-B27

Specific genetic allele highly associated with developing Ankylosing Spondylitis.

HLA-DRB1

Specific genetic allele strongly linked to an increased risk of Rheumatoid Arthritis.

Cell-Mediated Branch

Adaptive defense arm driven by T cells specializing in targeted cell killing and cytokine signaling.

Humoral Branch

Adaptive defense arm driven by B cells and circulating antibodies.

Double Negative (DN)

Early thymocyte stage in the cortex lacking both CD4 and CD8 surface markers.

Double Positive (DP)

Cortical thymocyte stage displaying both CD4 and CD8 markers while rearranging the TCR.

Positive Selection

Cortical gauntlet checking if a DP thymocyte can bind to a stromal cell; determines CD4 or CD8 lineage.

Negative Selection

Medullary gauntlet where self-reactive T cells binding tightly to self-antigens face forced apoptosis.

AIRE

Autoimmune Regulator transcription factor displaying tissue-specific self-proteins to bait T cells during negative selection.

T-Cell Receptor (TCR)

Membrane heterodimer (alpha/beta chains) restricted to seeing processed linear fragments on MHC.

CD3 Complex

Universal T-cell marker composed of six signaling chains driving intracellular alerts.

Polarizing Cytokines

Soluble chemical signals released by an APC during presentation to dictate what helper subset a T cell becomes.

Th1 Subset

Helper branch secreting IFN-gamma, IL-2, and TNF-beta to supercharge macrophages against intracellular threats.

Th2 Subset

Helper branch secreting IL-4, IL-5, and IL-13 to drive humoral antibody production and combat parasites.

Th17 Subset

Helper branch secreting IL-17 and IL-22 to recruit neutrophils to clear localized bacterial infections.

CD25

Essential surface activation marker found highly expressed on specialized Regulatory T cells (Tregs).

Surface Immunoglobulins (sIg)

Membrane-bound IgM and IgD functioning as the antigen-binding sites for B Cell Receptors.

B-Cell Coreceptor Complex

Cluster composed of CD19, CD21, and CD81 that amplifies intracellular activation signaling.

T-Independent Activation

Direct crosslinking of multiple BCRs by carbohydrate polymers; yields fast IgM but no memory.

T-Dependent Activation

Full activation pathway where a B cell presents to a Th cell; drives class-switching and memory cells.

CD40-CD40L

Critical surface ligand contact signal required between a B cell and a T helper cell during dependent activation.

Isotype

Structural heavy-chain variations determining the general class of an antibody (IgM, IgG, IgA, IgE, IgD).

Allotype

Minor genetic amino acid variations in constant regions found between individual members of the same species.

Idiotype

Unique hypervariable antigen-binding region variations specific to a single clone of B cells.

Heavy Chains

Large, central peptide chains determining antibody class (Gamma, Mu, Alpha, Delta, Epsilon).

Light Chains

Small outer peptide chains; can only be Kappa or Lambda throughout the structure.

Variable Region

Outer tips of the Y-shaped arms containing hypervariable spots for antigen binding.