Cell interaction- cytokines/cytokine therapy

Question 1

What is the definition of a cytokine?

Answer 1

proteins secreted by cells of the immune system whose function is to regulate the immune response by communication amongst cells

Question 2

How do cytokines differ from hormones?

Answer 2

hormones- low redundancy; homeostasis; ex.- insulin, glucagon, calcitonin; specific cell targets, source-specific cells in endocrine organs; effect- endocrine
cytokines- high redundancy; tissue repair, inflammation, immune response; ex.- interleukins, interferons, chemokines; many different cell targets (pleiotropy); source- many different cell types; effect- autocrine, paracrine, endocrine

Question 3

How are cytokines classified/named?

Answer 3

interleukins- regulate interactions between lymphocytes and other leukocytes
interferons- anti-viral function, produced in response to viral infection and other immune stimulation
TNF- immune function and anti-tumor activity
growth factors- regulate stem cell growth, hematopoiesis
chemokines- chemotaxis and leukocyte activation

Question 4

How do cytokines exert their effects?

Answer 4

autocrine- acts on same cell
paracrine- acts on nearby cells
endocrine- acts on cells in distant locations

Question 5

What are the functions of cytokines in general?

Answer 5

mediate and regulate the immune response and inflammation
not pre-formed, synthesized for a short period
influence the production of other cytokines
can act on many different cell types and produce different responses
redundancy

Question 6

What are the functions of some of the common cytokines?

Answer 6

mediate natural/innate immunity
regulate lymphocyte growth, activation and differentiation
activate inflammatory cells
chemotactic
hematopoietic

Question 7

What cells produce common cytokines?

Answer 7

macrophages, B lymphocytes, T lymphocytes and mast cells, as well as endothelial cells, fibroblasts, and various stromal cell

Question 8

Define Pleiotropy

Answer 8

cytokines can act on many different cell types and produce different responses

Question 9

Define Redundancy

Answer 9

many different cytokines may act on one cell type to induce one type of response

Question 10

How are cytokines regulated?

Answer 10

alteration of receptor expression on the target cell surface
by binding proteins which may bind up specific cytokines preventing their action
by other cytokines-cytokines that may exert opposite effects