External regulation of immune response

1. External regulation of immune response J. Ochotná

2. Causal treatment a) Stem cell transplantation • for serious congenital disorders of the immune system (some lymphoproliferative and myeloproliferative disorders) • complications: infectious complications                     Graft-versus-host • obtaining stem cells - collection from shovel hip bone                              - from umbilical cord blood                              - from peripheral blood after stimulation with GM-CSF

3. b) Gene therapy • with a suitable expression vector is introduced functional gene (to replace dysfunctional gen) into the lymphocytes or stem cells • used as a treatment for some cases of SCID

4. Substitution treatment • autologous stem cell transplantation followingchemotherapy and radiotherapy • treatment with intravenous immunoglobulin (derived from plasma of blood donors) • substitution of C1 inhibitor for hereditary angioedema • substitution of erythropoietin in patients with chronic renal failure • substitution of G-CSF in agranulocytosis

5. Immunomodulation = medical procedure to adjust the disrupted immune function Non-specific immunosuppressive therapy • nonspecific = affects not only autoreactive and aloreactive                        lymphocytes, but also other components of immunity (risk of reduction antiinfectious and anti- tumor immunity) • used for treatment of autoimmune diseases, severe allergic conditions and for organ transplantation

6. Non-specific immunosuppressive therapy • corticosteroids - anti-inflammatory, immunosuppressive effects                    - blocking the activity of transcription factors (AP-1, NFkB)                    - suppress the expression of genes (IL-2, IL-1, phospholipase A, MHC gp II, adhesion molecules)                   - inhibition of histamine release from basophils                    - higher concentrations induce apoptosis of lymfocytes • immunosuppressants affecting the metabolism of DNA - cyclophosphamide                          - methotrexate

7. immunosuppressant selectively inhibiting T lymphocytes - immunosuppressive ATB: cyclosporine A, tacrolimus, rapamycin (suppressing the expression of IL-2 and IL-2R in activated T lymphocytes)                 - monoclonal antibody anti-CD3 (Immunosuppression after transplantation, treatment of rejection crises) • immunoglobulins in the immunosuppressive indication- Polyspecific intravenous immunoglobulins                    (Inhibition of B lymphocytes, antiidiotype activity, inhibition of cytokines, neutralization of toxins, inhibition of complement activation ...)

8. Anti-inflammatory and antiallergic treatment • nonsteroidal anti-inflammatory drugs • antihistamines - blocking H1 receptor                          - reduce the expression of adhesion molecules                          - reduce the secretion of histamine ... • inhibitors of inflammatory cytokine - receptor antagonist for IL-1                          - monoclonal antibodies against TNF                          - thalidomide (TNF inhibitor) • enzyme therapy - in the enzyme mixture has a major effect trypsin and bromelain                            - anti-inflammatory and immunomodulatory effects

9. Non-specific immunostimulant therapy • synthetic immunomodulators • Methisoprinol (Isoprinosine) - used in viral infections with more severe or relapsing course • bacterial extracts and lysates • Broncho-Vaxom - prevention of recurrent respiratory tract infections • Ribomunyl • products of the immune system • IL-2 - renal adenocarcinoma • IFNa, IFNb - viral hepatitis, some leukemia • Erythropoietin – renal failure • G-CSF, GM-CSF – neutropenia • Transfer factor (blood donors leukocytes undergoing dialysis) • Thymus hormones

10. Antigen-specific immunomodulatory therapy • specific immunomodulation = induce an immune response or tolerance against a specific antigen a) active immunization= use of antigen to induce an immune response that can later protect against a pathogen bearing the antigen (or similar antigen) • immunization vaccines are made from inactivated or attenuated microorganisms or their antigens (polysaccharide capsule, toxins) • creates long-term immunity • activate cellular and antibody immunity • administration of antigen injectable, oral • prophylaxis • risk of causing infection or anaphylactic reactions

11. b) passive immunization • natural - transfer of maternal antibodies in fetal blood • therapeutically - the use of animal antibodies against various toxins (snake toxins, tetanus toxin, botulinum toxin) • prophylaxis - the human immunoglobulin from immunized individuals (hepatitis A, rabies, tetanus)                     - Anti-RhD antibodies - preventing maternal immunization with RhD+ fetus • provides a temporary (3 weeks) specific humoral immunity • the risk of induction anaphylactic reactions

12. c) specific immunosuppression= induction of tolerance against a specific antigen • ongoing clinical studies • induction of tolerance by oral administration of antigen (treatment of certain autoimmune diseases) • allergen immunotherapy (pollen, insect poisons) d) vaccination against cancer • s a promising approach appears to immunization dendritic cells

13. Defence against extracellular pathogens

14. Defence against extracellular pathogens • bacteria (gram-negative, gram-positive cocci, bacilli), unicellular parasites • for their elimination is necessary opsonization (C3b, lectins, antibodies ...) • neutrophilic granulocytes are chemotactic attracting to the site of the infection (C5a, C3a and chemotactic products of bacteria) • absorbed bacteria are destroyed by the microbicidal systems (products of NADP-H oxidase, hydrolytic enzymes and bactericidal substances in lysosomes)

15. phagocytes production of proinflammatory cytokines (IL-1, IL-6, TNF) that induce an increase in temperature, metabolic response of the organism and synthesis of acute phase proteins • in later stages of infection are stimulated antigen-specific mechanisms • plasma cells initially produce IgM isotype after isotype switching produce IgG1 and IgA (opsonization) • sIgA protect against intestinal and respiratory infections by bacteria • bacteria with a polysaccharide capsule may cause T-independent IgM antibody production (after the establishment to the bacteria activate the classical complement path)

16. after infection persist IgG, IgA (protective effect) and memory T and B lymphocytes • in the defense against bacterial toxins apply neutralizing antibodies (Clostridium tetani and botulinum ...) • "indirect toxins - bacterial Lipopolysaccharide (LPS) stimulates big number of monocytes to release TNF, which can cause septic shock • extracellular bacterial infections are especially at risk individuals with disorders in the function of phagocytes, complement and antibody production

18. Defence against intracellular pathogens

19. Defense against intracellular pathogens • bacteria, fungi and unicellular parasites • intracellular parasitism is given by the ability of microorganisms to escape microbicidal mechanisms of phagocytes • macrophages, which absorbed them, produce IL-12 → TH1 differentiation, production of IFNg and membrane TNF → activation of macrophages and induction of iNOS • plasma cells under the influence of IFNg produce IgG2, immune complexes containing IgG2 bind to Fc receptors on macrophages and thus stimulate them-

20. in the defense against intracelular parasites, which escape from phagolysosomes apply TC lymphocytes • intracellular microorganisms infections are at risk individuals with certain disorders of phagocytes and defects of T lymphocytes

21. Anti-viral defence

22. Anti-viral defence • interferons - in infected cells is induced production of IFNa and IFNb (prevents viral replication and in uninfected cells cause the anti-virus status); IFNg stimulates the conversion to activated macrophages (iNOS) • NK cells - ADCC (Antibody-dependent cell-mediated cytotoxicity) = cytotoxic reaction depends on the antibodies; the NK-lymphocyte recognizes cell opsonized with IgG by stimulation Fc receptor CD16 and then activate cytotoxic mechanisms (degranulation) • infected macrophages produce IL-12 (a strong activator of NK cells)

23. in the defense against cytopathic viruses mostly applied antibodies: • sIgA inhibit mucosal adhesion of viruses (defense against respiratory viruses and enteroviruses) • neutralizing IgG and IgM antibodies activate the classical way of complement, which is capable of some viruses lysis • IgA and IgG derived in viral infection have a preventive effect in secondary infection

24. effector TC lymphocytes destroy infected cells in direct contact (granzym/perforin; FasL) and by produced cytokines (lymfotoxin) • some viruses after infection integrate into the host genome, where persist for years (varicella zoster, EBV, papillomavirus) • by these infections are at risk individuals with T lymphocyte immunodeficiency and with combined immune disorders • increased susceptibility to herpes infections in individuals with dysfunction of NK cells

25. Defense against multicelular parasites

26. Defense against multicelular parasites • contact of mast cells, basophils and eosinophils with parasite antigens • TH2 stimulation under the influence of IL-4 (mast cells and other APC stimulated by parasite) • TH2 stimulate B cells with BCR-specific parasite antigens • isotype switching under the influence of IL-4 to IgE • IgE bind to FceRI on mast cells and basophils („antigen-specific receptors“)

27. establish of multivalent antigen (multicellular parasite) using the IgE to highafinity Fc receptor for IgE (FcRI) aggregation of several molecules FcRI • initiate mast cell degranulation (cytoplasmic granules mergers with the surface membrane and release their contents) • activation of arachidonic acid metabolism (leukotriene C4, prostaglandin PGD2) - amplification of inflammatory responses • start of production of cytokines (TNF, TGF, IL-4, 5,6 ...) by mast

28. in later stages are activated TH1 and are produced antibodies of other classes • eosinophils fagocyte complexes of parasitic particles with IgE via their receptors for IgE • eosinophils use against parasites extracellular bactericidal substances released from granules (eosinophil cationic protein, protease)

29. Activation of mast cell

30. Tumour immunology

31. Malignant transformation • failure of regulation of cell division and regulation of "social" behavior of the cells • the uncontrollable proliferation, dissemination to other tissues • mutations in protoonkogenes and antionkogenes Tumor cells • unlimited growth (loss of contact inhibition) • growth without stimulating growth factors • immortality (cancer cells have not a limited number of generations as normal cells) • often altered number of chromosomes as frequent chromosomal alteration • TSA ...

32. Tumor antigens • Antigens specific for tumors (TSA) • complexes of MHCgp I with abnormal fragments of cellular proteins- chemically induced tumors - leukemia with chromosomal translocation • complexes of MHCgp with fragments of proteins of oncogenic viruses- tumors caused by viruses (EBV, SV40, polyomavirus) • abnormal forms of glycoproteins- sialylation of surface proteins of tumor cells • idiotypes of myeloma and lymphoma- clonotyping TCR and BCR

33. b) Antigens associated with tumors (TAA) • present also on normal cells • differences in quantity, time and local expression • auxiliary diagnostic markers 1)onkofetal antigens • on normal embryonic cells and some tumor cells • -fetoprotein (AFP) - hepatom • canceroembryonal antigen (CEA) - colon cancer 2) melanoma antigens • MAGE-1, Melan-A

34. 3) antigen HER2/neu • receptor for epithelial growth factor • mammary carcinoma 4) EPCAM • epithelial adhesion molecule • metastases 5) differentiation antigens of leukemic cells • present on normal cells of leukocytes linage • CALLA -acute lymphoblastic leukemia (CD10 pre-B cells)

35. Anti-tumor immune mechanisms Immune control • tumor cells normally arise in tissues and are eliminated by T lymphocytes • probably wrong hypothesis Defensive immune response • tumor cells are weakly immunogenic • occurs when tumor antigens are presented to T lymphocytes by dendritic cells activated in the inflammatory environment • if tumor cells are detected, in defense may be involved non-specific mechanisms (neutrophilic granulocytes, macrophages, NK cells) and antigen-specific mechanisms (complement activating antibodies or ADCC, TH1 and TC)

36. cancer-associated antigens are processed by APC and recognized by T lymphocytes in complex with HLA I. and II. class with providing costimulus signals • predominance of TH1(IFN g, TNFa) • specific cell-mediated cytotoxic reactivity –TC • activation of TH2 → support B lymphocytes→ tumor specific antibodies (involved in the ADCC) • tumor cells are destroyed by cytotoxic NK cells (ADCC)

37. Mechanisms of tumor resistance to the immune system - • high variability of tumor cells • low expression of tumor antigens • sialylation • tumor cells signals do not provide costimulus → T lymphocyte anergy • some anticancer substances have a stimulating effect • production of factors inactivating T lymphocytes • expression of FasL → T lymphocyte apoptosis • inhibition of the function or durability dendritic cells (NO, IL-10, TGF-b)