Cytokines Lecture Vocabulary

Vocabulary flashcards summarizing key terms, families, receptors, and functions of cytokines as covered in the lecture.

Cytokine

Small protein messenger that mediates communication between immune cells.

Autocrine action

Cytokine binds to receptors on the same cell that secreted it.

Paracrine action

Cytokine affects nearby cells in the local environment.

Endocrine action

Cytokine enters circulation to act on distant target cells.

Signalling pathway

Intracellular cascade triggered after cytokine-receptor binding, leading to gene transcription changes.

Hematopoietin family

Large cytokine family that supports blood cell growth and immune cell differentiation (e.g., IL-2, IL-3).

Tumor Necrosis Factor (TNF) family

Cytokines involved in inflammation, cell activation, and apoptosis (e.g., TNF-α, FasL).

Interferon family

Cytokines with antiviral and immunomodulatory activities (IFN-α, IFN-β, IFN-γ, IL-10).

Chemokine family

Cytokines whose primary role is directing cell migration (chemotaxis).

IL-2

T-cell growth factor; activates T cells, NK cells, monocytes, and promotes B-cell proliferation.

IL-2 receptor α-chain (CD25)

Component that converts IL-2 receptor from low to high affinity upon T-cell activation.

TNF-α

Major pro-inflammatory cytokine that induces adhesion molecules, promotes clotting, and stimulates other cytokines.

Fas Ligand (FasL)

TNF-family member that binds Fas to induce apoptosis in target cells.

CD40 Ligand (CD40L)

TNF-family cytokine on activated T cells that licenses B-cell class switching and macrophage activation.

IFN-α / IFN-β

Type I interferons that induce antiviral states in infected and neighboring cells.

IFN-γ

Type II interferon produced by TH1 and NK cells; activates macrophages and promotes IgG class switching.

Chemokine structural groups

CXC, CC, C, CX3C—classified by cysteine motif pattern.

CXCL8 (IL-8)

CXC chemokine that mobilizes and attracts neutrophils to infection sites.

CCL2 (MCP-1)

CC chemokine that recruits monocytes, NK cells, and T cells; linked to chronic inflammation.

CX3CL1 (Fractalkine)

CX3C chemokine that mediates leukocyte adhesion and brain inflammation.

Affinity

Strength of binding between cytokine and its receptor; high affinity yields strong signalling.

Hematopoiesis

Formation of blood cellular components; regulated by cytokines such as IL-3 and GM-CSF.

Prothrombotic action

Cytokine-induced enhancement of blood clot formation (e.g., TNF-α effect).

TH1 cytokine profile

Dominated by IFN-γ, IL-2; drives cell-mediated immunity and macrophage activation.

TH2 cytokine profile

Includes IL-4, IL-5; promotes B-cell help and antibody class switching to IgE and IgA.

Class switching

Cytokine-guided process where B cells change antibody isotype (e.g., IL-4 → IgE, TGF-β → IgA).

GM-CSF

Cytokine that stimulates production and differentiation of granulocyte-macrophage progenitors.

Adhesion molecules

Endothelial surface proteins up-regulated by TNF-α to facilitate leukocyte binding and extravasation.

Chemotaxis

Directed movement of cells toward a chemokine gradient.

Diapedesis

Passage of leukocytes through blood-vessel walls into tissues, aided by cytokines and chemokines.

Cytokine receptor

Cell-surface protein complex that specifically binds a cytokine to initiate signalling.

Negative regulation

Cytokine-mediated suppression of other immune responses (e.g., IFN-γ inhibits TH2 expansion).