Cytokines in Immunology Quiz

Study Notes

Cytokines are low-molecular weight regulatory proteins or glycoproteins, generally less than 30 kDa.
Some cytokines are interleukins, indicating secretion by leukocytes and acting on other leukocytes (e.g., IL-2).
Colony-stimulating factors (e.g., M-CSF, G-CSF) support cell proliferation.
Tumor necrosis factors (e.g., TNF-α) have cytotoxic activity towards transformed cells.
Interferons (e.g., IFN-γ) interfere with viral replication.
Chemokines (e.g., CCL2) affect chemotaxis and leukocyte behavior.

Colony-stimulating factors (CSFs) are a type of cytokine.
GM-CSF affects granulocyte and monocyte lineages.
M-CSF affects monocyte lineages.
G-CSF affects granulocyte lineages.
IL-3 induces proliferation and differentiation of both early pluripotent stem cells and committed progenitors.

IL-3, also known as multispecific hemopoietin, is naturally produced by Th1 and Th2 lymphocytes, mast cells, and eosinophils.
IL-3 stimulates the production of macrophages, granulocytes, and dendritic cells from bone marrow precursors.
IL-3 is a secreted monomeric glycoprotein synthesized almost exclusively by T cells in response to antigen stimulation.
IL-3 has only modest effects alone; its effects are enhanced in conjunction with other growth factors.

Interferon gamma (IFN-γ) is critical to both innate and adaptive immunity.
IFN-γ acts as the primary activator of macrophages, stimulating natural killer cells and neutrophils.
IFN-γ induces Th1 cell activation and M1 polarization of macrophages.
IFN-γ increases macrophage phagocytosis, tumoricidal activity, and intracellular killing of pathogens.
IFN-γ is important for the effector functions of cytotoxic T cells.

Proinflammatory cytokines (e.g., TNF-α, IL-1, IL-6, IL-8, IL-12) are predominantly produced by activated macrophages.
They increase the inflammatory response.

Interleukin-1 (IL-1) is the first interleukin identified as a potent proinflammatory molecule.
IL-1 is involved in host responses in infections and inflammation, and activates innate and adaptive lymphoid cells.
The IL-1 system is tightly regulated at various levels to balance innate immunity with inflammation.

IL-1, an endogenous pyrogen, affects the hypothalamus, increasing body temperature (fever).
IL-1 influences joint diseases, such as rheumatoid arthritis, as well as tumor growth and promotes hematopoiesis and CSF (colony stimulating factor) production by bone marrow stromal cells.
IL-1 is primarily produced by macrophages, but also endothelial and epithelial cells.

Interleukin-6 (IL-6) has pleiotropic effects on inflammation, immune response, and hematopoiesis.
IL-6 is a significant proinflammatory cytokine produced by T cells, activated macrophages, and adipose tissue.
IL-6 promotes the differentiation of activated B cells into plasma cells.
The name "hepatocyte-stimulating factor (HSF)" was given to IL-6 for its effect on acute phase protein synthesis in hepatocytes.

Interleukin-2 (IL-2), a cytokine produced by helper T cells during an immune response, is crucial for the growth, proliferation, and differentiation of naive T cells into effector T cells.
IL-2 was initially called T-cell growth factor.
IL-2 stimulates proliferation and enhances the function of other T cells, natural killer (NK) cells, and B cells.

IL-8: Also known as neutrophil chemotactic factor, involved in chemotaxis and phagocytosis of neutrophils.
IL-9: Secreted by Th9 cells, roles in tumors, inflammatory diseases, and parasite infections. It is involved in antitumor responses.
IL-17: Mediates initial antibacterial and antifungal responses through activity of TH17 cells. It links T cell activation to neutrophil mobilization and activation.