1. Agents Which Affect the Immune Response
Dan Fernandez

2. Overview I. Immune System Overview II. History of Immunology
III. Current Treatment Techniques
Immunosuppressants
Tolerogens
Immunostimulants
Immunization
IV. What the future holds
V. Conclusion

3. History of Immunology
430 BC: Earliest known mention of immunity during the plague of Athens
Thucydides noted that recovered individuals could help nurse the sick without getting the illness a second time
University of Maryland conference concluded that typhus was the causative disease, though its still up for debate
18th Century: Scientist de Maupertuis experimented with scorpion venom and found some mice and dogs were immune to effects.
Louis Pasteur later exploited these observations in developing vaccination and germ theory of diseases.
1891: Robert Koch published proof that microorganisms caused infectious diseases
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4. History of Immunology Paul Erlich
Noted for curing syphilis and research into autoimmunity
Side-Chain Theory: explained effects of serum and enabled measurement of antigen
Coined term “chemotherapy”
Work showed the existence of a blood brain barrier
Popularized concept of “magic bullet”
Target specifically a bacterium without affecting other organisms
Salvarsan
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5. History of Immunology Ilya Ilyich Mechnikov
Received nobel prize in 1908 for his work on phagocytosis
Realized digestion was basically same mechanism done by white blood cells to engulf and destroy harmful bacteria
Current popular thought was that white blood cells actually helped spread the ingested pathogens around the body
Also believed that aging is caused by toxic bacteria in gut and that lactic acid could help prolong life
Drank sour milk everyday
Thought inspired Minoru Shirota to investigate relationship between bacteria and good intestinal health
This led to marketing of fermented milk drinks, a.k.a. Probiotics
Neutrophils hunt and kill white blood cells. Staph a have been added. Bacteria release chemoattractant sensed by the neutrophil, which becomes polarized and starts chasing the bacteria. Thermal energy moves the bacteria in a random path. When the neutrophil catches the bacteria, it engulfs the bacteria by phagocytosis
Neutrophil Chase

6. Immune System Overview
Two types of Immune Response
Non-specific (Basically just recognizes foreign vs native)
Barriers
Inflammation
Phagocytes
All types of White Blood Cells (Leukocytes)
Dendritic Cells
Macrophages
Neutrophils

7. Immune System Overview
Specific (Adaptive) Response
Lymphocytes (also types of white blood cells)
B Lymphocytes (B Cells)
Produced in bone marrow
Humoral Response
Before Infection/Infiltration
T Lymphocytes (T Cells)
Start in bone marrow, but mature in Thymus
Cell Mediated Response
Helper T Cells
Cytotoxic T Cells
Once activated, T Cells and B Cells differentiate and divide
Causes cytokine and lymphokine release

8. B-Cells Have membrane-bound antibodies on cell surface Make antibodies
Variable and specific for each B-Cell
Make antibodies
Activation:
Antigen must bind to sites
Stimulation by Helper T-Cells

9. T-Cells Helper T Cells Cytolytic T Cells T-Regulatory Cells (Tregs)
Respond to nearly all antigens,
Produce CD4, which helps bind to class II MHC complexes on antigen presenting cells
Cytolytic T Cells
Main response towards infected and cancerous cells
Produce CD8 protein, binds transplanted tissue, infected cells, cancer cells
Secrets proteins that cause cell death
T-Regulatory Cells (Tregs)
Suppress the activation of the immune system to help maintain homeostasis

10. Rheumatoid Arthritis
Disease that leads to inflammation of the joints and surrounding tissues
Can affect organs
The immune system confuses healthy tissue with foreign and begins to attack itself
Occurs at any age, usually affects women more than men
Affects joints on both sides equally
Wrists, fingers, knees, feet, ankles

11. Systemic Lupus Erythematosus
Autoimmune disease
Symptoms:
Chest pain, fatigue, fever, general discomfort, hair loss, mouth sores, sensitivity to sunlight, skin rash, swollen lymph nodes, arrhythmias, blood in urine, abdominal pain, coughing up blood, patchy skin colors
Other form: lupus nephrititis
Can cause kidney failure and lead to dialysis

12. Other Immunological Diseases
Type I diabetes mellitus
Multiple sclerosis
Asthma
Allergies
SCID

13. Treatment Strategies
Immunosuppression – involves downregulating immune system activity
Tolerance – the idea that a body can be taught not to reject somthing
Immunostimulation – involves upregulating immune system activity
Immunization – active or passive
It depends on the disease which one you will use to treat. As such, it’s easy to sort of classify the drugs under a wide umbrella:
-suppressants will be used when the immune system is overactive, like in auto-immune disorders, and used to help prevent transplant rejection
-tolerance involves inducing and maintaining tolerance
-stimulation will be used in diseases where there’s an immune deficiency, in order to stimulate the body to do what it was built to do

14. Immunosuppression – Glucocorticoids
Usually co-administered with other suppressive agents to treat auto-immune disorders or treatment of transplant rejection
Exact mechanism not elucidated
Very broad anti-inflammatory effects
Downregulate IL-1 and IL-6
Cause apoptosis in activated cells
IL-1 and IL-6 are pro-inflammatory agents

15. Immunosuppression – Glucocorticoids
Side Effects
Toxic
Causes increased infection risk
Poor wound healing
Hyperglycemia
Hypertension
Increased infection risk occurs with all immunosuppressants, as they decrease your body’s natural defenses. Must be careful!

17. Immunosuppression – Glucocorticoids
Prednisone
Dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant. It is 20 to 30 times more potent than the naturally occurring hormone cortisol and 4 to 5 times more potent than prednisone.
Cortisol

18. Immunosuppression – Calcineurin Inhibitors
Calcineurin – protein phosphatase that activates T Cells by dephosphorylating transcription factors, including NFAT (nuclear factor of activated T cells).
Blocks T Cell proliferation
Decreased immune response
When an antigen-presenting cell interacts with a T cell receptor on T cells, there is an increase in the cytoplasmic level of calcium, which[2] activates calcineurin, by binding a regulatory subunit and activating calmodulin binding. Calcineurin induces different transcription factors (NFATs) that are important in the transcription of IL-2 genes. IL-2 activates T-helper lymphocytes and induces the production of other cytokines. In this way, it governs the action of cytotoxic lymphocytes and NK cells. The amount of IL-2 being produced by the T-helper cells is believed to influence the extent of the immune response significantly.

19. Immunosuppression – Calcineurin Inhibitors
Tacrolimus
a.k.a. FK-506
Tacrolimus – Prograf®; macrolide antibiotic with greater efficacy than most Calcineurin inhibitors b/c it’s easy to monitor blood levels.
It forms a complex with tacrolimus-FKBP-12, Ca+2, calmodulin, and calcineurin, which inhibits the phosphatase activity of calcineurin.
Cyclosporine A has similar mechanism to Tacrolimus
Cyclosporin A

21. Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs
Inhibit immune cell proliferation, reducing the immune response
mTOR inhibitors
Enzyme in lymphocyte cell that is key to transition from G1 to S phase

22. Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs
Sirolimus administered with glucocorticoids, have a synergistic effect
Everolimus
Sirolimus

23. Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs
Azathioprine
Purine anti-metabolite
Tioguanine
Mercaptopurine
Azathioprine
Guanine

24. Immunosuppression – Anti-proliferative and Anti-Metabolic Drugs
Mycophenolate Mofentil (CellCept®)
Hydrolyzed to mycophenolic acid
IMPDH inhibitor (inosine monophosphate dehydrogenase enzyme
Important in biosynthesis of guanine
Good alternative to azathioprine when toxicity is an issue
Mycophenolic acid

25. Immunosuppression – Monoclonal Antibodies
Anti-CD3 Antibodies
Binds to chain of CD3, which is involved in T-cell antigen recognition, signaling, and proliferation
Administration of mAb followed by depletion of T cells from bloodstream and lymphoid organs
Lack of IL-2 production
Reduction of multiple cytokines
Not IL-4 and IL-10
Used to treat organ transplant rejection
Muromonab-CD3 (Orthoclone OKT3®)

26. Immunosuppression – Monoclonal Antibodies
Anti-IL-2 Receptor [Anti-CD25] Antibodies
Exact mechanism not understood
Binds to IL-2 receptor on surface of activated T cells
No effect on resting T cells
Stops current response
Daclizumab and Basiliximab

27. Immunosuppression – Monoclonal Antibodies

28. Immunosuppression – Other Agents
Others include
Alemtuzumab (mAb) – targets CD52, causes lympholysis by inducing apoptosis of targeted cells
IL-1 Inhibition
Alefacept – protein, interferes with T-cell activation

29. Tolerance Strategy is to induce and maintain tolerance
Useful strategy for organ transplantation
Very much the target of research today
Would represent a true cure for autoimmune conditions without side effects of immunosuppressive agents
“Holy Grail” of immunomodulation

30. Tolerance Co-Stimulation Donor Cell Chimerism
Requires two signals to activate
Donor Cell Chimerism
Co-existence of two genetic lineages in a single individual
First dampen or eliminate immune function with ionizing radiation, drugs, or antibodies
The provide new source of immune function by transfusion
Shows promise in development of long-term unresponsiveness

31. Immunostimulants
Immunostimulants are applicable during infections, immunodeficiency, and cancer
Levamisole
Restores depressed immune function of B and T Cells, monocytes, and macrophages
Causes agranulocytosis
Removed from market in 2005
Agranulocytosis – severe and dangerous lowered white blood cell count
Levamisole

32. Immunostimulants Thalidomide Teratogenetic
BUT is useful to treat erythema nodosum leprosum and multiple myeloma
Multiple Myeloma – cancer of plasma cells (B cells that make antibodies)
Erythema nodosum leprosum – inflammation of fat cells under the skin characterized by red nodules or lumps
Thalidomide

33. Immunostimulants Interferons
Bind to spefici cell-surface receptors that initiate series of intracellular events
Induction of enzymes
Inhibition of cell proliferation
Enhancement of immune activity
Intron A ® - peptide used for tumor treatment and infectious diseases;
Actimmune ® - peptide that activates phagocytes and induces generation of oxygen metabolites that are toxic to a number of microorganisms

34. Immunization Active or passive
Active – stimulation with antigen to develop antigens for future prevention
Passive – administration of antibodies to individual already exposed or about to be exposed to antigens
Vaccines – active; administration whole, killed organism, live organism, or specific peptide from organism
Immune Globulin – used in passive immunization; used in individuals deficient in antibodies

35. Future
More research into Tolerance may yield less immunological diseases
Always looking for more specific targets
Less toxic compounds needed with less side effects

36. Conclusion Most immunomodulatory drugs are suppressants
Cause problems as it makes patients more susceptible to infection
Most are somewhat toxic
Tolerance is a great concept but not yet fully realized
Stimulants are helpful to boost the immune system
Immunization has been a proven tool against fighting infectious diseases

37. References
Besedovsky, Hugo O., and Adriana Del Rey. "Regulating Inflammation by Glucocorticoids." Nature Immunology 7.6 (2006): Print.
Campbell, Neil A., and Jane B. Reece. "43. The Immune System." Biology. 7th ed. San Francisco: Pearson, Benjamin Cummings, Print.
Goodman, Louis Sanford, Laurence L. Brunton, Bruce Chabner, and Björn C. Knollmann. "35. Immunosuppressants, Tolerogens, and Immunostimulants." Goodman & Gilman's The Pharmacological Basis of Therapeutics. 12th ed. New York: McGraw-Hill Medical, Print.
Hamawy, MM. "Molecular Actions of Calcineurin Inhibitors." Drug News & Perspectives 16.5 (2003): Print.
Marder, Wendy, and W. McCune. "Advances in Immunosuppressive Therapy." Seminars in Respiratory and Critical Care Medicine (2007): Print.  

38. Reading Assignment
Hamawy, MM. "Molecular Actions of Calcineurin Inhibitors." Drug News & Perspectives 16.5 (2003): Print.
Marder, Wendy, and W. McCune. "Advances in Immunosuppressive Therapy." Seminars in Respiratory and Critical Care Medicine 28.4 (2007): Print.  

39. Homework Questions
Who were the two main fathers of modern immunology and what were their major contributions?
What is the mechanism of action of Azathioprine?
What is the mechanism of action of Leflunomide?
Explain the Calcium-calcineurin cascade.