BIOL 344 Exam 1 Vocabulary Flashcards

Vocabulary flashcards generated for BIOL 344 Exam 1 covering key terms, definitions, and concepts from Lectures 1 through 8.

Self-Renewal

The capacity of a hematopoietic stem cell to divide and produce additional stem cells, preventing the stem cell pool from becoming depleted.

Multipotency

The capacity of a hematopoietic stem cell to differentiate into all distinct blood cell lineages.

CD Nomenclature

Cluster of Differentiation system used to classify cell-surface molecules recognized by specific monoclonal antibodies to define cellular phenotypes.

Microglia

Tissue-resident macrophages in the central nervous system that survey brain tissue and prune synapses.

Kupffer Cells

Tissue-resident macrophages located in liver sinusoids that clear material from portal blood.

Alveolar Macrophages

Tissue-resident macrophages located in lung airspaces that clear inhaled particles.

Osteoclasts

Specialized macrophages located in bone tissue that function to resorb bone.

Langerhans Cells

Tissue-resident antigen-sampling cells located in the epidermis.

Red Pulp Macrophages

Macrophages in the red pulp of the spleen that clear debris and remove old red blood cells.

Mesangial Cells

Specialized macrophages in the kidney glomerulus that clear trapped immune complexes.

Primary Lymphoid Organs

Anatomical sites, such as the bone marrow and thymus, where lymphocytes are generated and educated before encountering foreign antigen.

Secondary Lymphoid Organs

Anatomical sites, such as lymph nodes, spleen, and Peyer's patches, where mature lymphocytes encounter antigen and initiate adaptive immune responses.

Positive Selection

A thymic cortex process testing whether developing T cells can recognize self-MHC; cells unable to bind self-MHC die by neglect.

Negative Selection

A thymic medulla process where T cells that bind too strongly to self-MHC or self-peptides are deleted to prevent autoimmunity.

DiGeorge Syndrome

A condition caused by a 22q11.2 chromosomal deletion resulting in a missing or underdeveloped thymus, leading to severely reduced T cell counts with normal B cell development.

High Endothelial Venule (HEV)

Specialized blood vessel endothelium through which naive lymphocytes exit the bloodstream to enter secondary lymphoid tissues like lymph nodes.

Rolling

The first step of leukocyte extravasation in which selectins form weak, reversible bonds with passing leukocytes to slow them down along the endothelium.

Natalizumab

A therapeutic antibody that blocks $\alpha4$ integrin to prevent leukocyte arrest and migration into the CNS, which also reduces immune surveillance and increases the risk of PML.

Fingolimod

A drug that internalizes the S1P receptor on lymphocytes, blocking their exit from lymph nodes and causing peripheral lymphopenia.

PAMP (Pathogen-Associated Molecular Pattern)

Conserved, structural, and essential molecular patterns produced by microbes (e.g., LPS, peptidoglycan) that are recognized by innate pattern recognition receptors.

DAMP (Damage-Associated Molecular Pattern)

Host molecules released or exposed during cell damage or unprogrammed death (e.g., HMGB1, extracellular S100) that trigger innate pattern recognition receptors due to abnormal location.

MyD88

An essential adaptor protein recruited by most Toll-like receptors that brings in IRAK4 and initiates signaling to activate NF-$\kappa$B and produce inflammatory cytokines.

TRIF

An adaptor protein utilized by TLR3 and TLR4 that signals through TBK1 and IRF3 to drive the transcription of type I interferons.

NF-$\kappa$B

A rapid-acting transcription factor sequestered in the cytoplasm by I$\kappa$B until I$\kappa$B is phosphorylated and degraded, allowing NF-$\kappa$B to move to the nucleus and turn on inflammatory genes.

Type I Interferons

Cytokines (IFN-$\alpha$ and IFN-$\beta$) secreted by virus-infected cells that bind IFNAR on neighboring cells to activate JAK/STAT signaling and establish an antiviral state.

Inflammasome

A cytosolic multiprotein complex (such as NLRP3-ASC-caspase-1) that activates caspase-1 to cleave pro-IL-1$\beta$ and pro-IL-18 into active forms and cleaves gasdermin D to trigger pyroptosis.

Pyroptosis

A form of inflammatory cell death caused by gasdermin D pore formation in the plasma membrane, resulting in cell rupture and release of active IL-1$\beta$ and DAMPs.

Endotoxin Tolerance

A state of temporary hyporesponsiveness in macrophages induced by continuous exposure to LPS, mediated by accumulated negative feedback signaling inhibitors.

Trained Immunity

An enhanced innate immune memory state in myeloid cells and progenitor marrow cells mediated by stable epigenetic modifications rather than gene rearrangement.

Zymogen

An inactive enzyme precursor that requires proteolytic cleavage by an upstream enzyme to become functionally active.

C3 Convertase

An enzymatic complex (C4b2a in classical/lectin pathways; C3bBb in alternative pathway) that cleaves complement protein C3 into C3a and C3b.

Opsonization

The covalent attachment of complement fragments (such as C3b) or antibodies to a target surface, providing binding handles for phagocytic receptors.

Anaphylatoxins

Small complement cleavage fragments (C3a and C5a) that bind GPCRs on leukocytes, endothelium, and mast cells to induce vascular permeability, degranulation, and inflammation.

Membrane Attack Complex (MAC)

A lytic pore complex assembled from complement proteins C5b, C6, C7, C8, and polymerized C9 that inserts into lipid membranes to cause osmotic cell lysis.

DAF (CD55)

A host cell membrane-bound regulatory protein that accelerates the decay and dissociation of surface-bound C3 convertases.

Factor I

A constitutively active soluble serum protease that cleaves and inactivates C3b and C4b in the presence of membrane-bound host cofactors.

CD59 (Protectin)

A host membrane-bound regulatory protein that prevents C9 polymerization and insertion into host cell membranes, blocking final MAC assembly.

Pleiotropy

The property of a single cytokine having different biological effects on different target cell types.

Redundancy

The property of multiple distinct cytokines exerting similar or identical functional actions on target cells.

Affinity

The intrinsic binding strength between a single antigen-binding site on a receptor or antibody and a single epitope.

Avidity

The cumulative total binding strength resulting from multiple simultaneous binding interactions between multivalent antigens and multivalent receptors or antibodies.

Cross-Reactivity

The binding of an antibody or antigen receptor to an epitope on an unrelated molecule that structurally resembles the original immunogenic epitope.