1. Cytokines: low-molecular-weight proteins secreted by WBC or other cell types in response to a number of stimuli.
Interleukins (IL): cytokines that are secrected by leukocytes and act upon other leukocytes.
Chemokines: cytokines that stimulate the migration and activation of cells, especially phagocytes and lymphocytes. They have a central role in inflammatory responses.

3. Most cytokines exhibit autocrine and/or paracrine action

4. Properties of Cytokines:
Pleiotrophy
Redundancy
Synergy
Antagonism
Cascade induction

6. REDUNDANCY

8. ELISA assay of cytokines

10. Cytokines Belong to 4 Structural Families:
Hematopoietin family
Interferon family
Chemokine family
Tumor necrosis factor family

13. The two major
cytokine producers;
TH cell and macrophage

15. Cytokine Receptors Belongs to 5 Families:
Immunoglobulin superfamily receptors
Hematopoietin receptor family
Interferon receptor family
TNF receptor family
Chemokine receptor family

21. Subfamilies in Class I Cytokine Receptors

22. CNTF: ciliary
Neurotrophic factor
LIF/OSM: leukemia-
Inhibitory factor/
oncostatin

26. Antagonistic Effects between Cykotines

30. Cytokine Antagonists
IL-1 receptor antagonist (IL-1Ra): binds to the IL-1 receptor but has no activity.
Soluble IL-2 receptor (sIL-2R): a segment of the a subunit that can bind to IL-2 and prevent its interaction with membrane-bound IL-2 receptor.
Viral mimics of cytokines and cytokine receptors

31. Suppress TH1
response

32. TH1 and TH2 cells can be identified in vitro by the cytokines they secrete:
TH1 cells promote cell-mediated immunity (e.g., activation of TC cells and delayed-type hypersensitivity) and the production of opsonization IgG antibodies. They are also associated with inflammation.
TH2 cells stimulate eosinophil activation and differentiation and promote humoral response (secretion of IgM and IgE antibodies). They are related to allergic reactions.

35. Cytokine-mediated generation and cross regulation of TH subsets

36. Cross-regulation between IFN-g and IL-4

37. The TH1/TH2 Balance Determines Disease Outcomes
Leprosy: a disease caused by an intracellular pathogen Mycobacterium leprae.
Tuberculoid leprosy: a cell-mediated immune response forms granulomas, resulting in the destruction of most of the mycobacteria.
Lepromatous leprosy: humoral response dominates, sometimes resulting in hypergammaglobulinemia. High numbers of the bacteria in macrophages. The infection will progress and spread into the bone and cartilage with extensive nerve damage.

39. Cytokine-related Diseases
Bacterial septic shock: endotoxin in cell wall of gram-negative bacteria stimulate macrophages to over produce IL-1 and TNF-a.
Bacterial toxic shock: caused by superantigens that bind simultaneously to MHC class II and TCR Vb domain. 5-25% of total T cells may respond to a single superantigen and result in excessive production of cytokines.

40. Strategies help to prolong the survival of heart transplants

42. Cytokines in hematopoiesis