Antigen presentation

1. Antigen presentation

2. Antigen presentation

3. Antigen recognition

4. Antigen presentation to T cells Signal TCR – MHC gp I+Ag peptid (APC) Co-stimulatory signal CD 28 (T lymphocyte) – CD 80, CD 86 (APC)

5. TH1 based immune response

6. TH1 immune response - inflammatory reaction • The role of TH1 cells is cooperation with macrophages and their transformation in activated, which are capable to produce NO through which destroy its intracellular parasites • For the conversion to activated macrophages are essential cytokines (IFNg) produced by TH1 cells

7. Activated macrophages secrete some cytokines (IL-1, TNF, ...) that help to stimulate T cells and stimulate local inflammation, which helps suppress infection • Interaction between TH1 cells and macrophages is a fundamental mechanism of delayed-type immunopathological reactions (DTH Delayed-type hypersensitivity) • The infected macrophage produces protein fragments derived from intracellular parasites, some of which are presented on the surface by MHC gp class II

8. Macrophages and dendritic cells stimulated by certain microorganisms produce IL-12 • TH precursor, which detects the infected macrophage and receives signals through the TCR, CD 28 and receptor for IL-12 and other adhesion and signaling molecules proliferates and differentiates to the effector TH1 cells that produce IFNg and IL-2. • IFNg promotes transformation of macrofages in activated IL-2 is an autocrine growth factor for TH1 cells

9. Interaction between APC and TH precursor

10. TH2 based immune response

11. TH2 immune response – help to B-lymphocytes • The basic function of TH2 cells is the cooperation with B lymphocytes (which were stimulated by Ag) by cytokines (IL-4, IL-5, IL-6) and direct intercellular contact • For stimulation of B lymphocytes is usually necessary cooperation between APC → TH2 cell → B lymphocyte • In the case of the minimal model, where the B cell becomes a good APC (CD80, CD86) is sufficient cooperation between TH2 cell → B lymphocyte

12. TH precursor, which detects the infected macrophage and receives signals through the TCR, CD 28 receptor for IL-4 receptor and IL-2 and other adhesion and signaling molecules proliferates and differentiates in the effector TH2, which provide B lymphocytes auxiliary signals via cytokines secreted by IL-4, IL-5, IL-6 and adhesion molecules through CD 40L, which bind to the costimulatory receptor on B lymphocytes CD 40 • Interaction between CD40 (B lymphocytes) and CD40L (TH2 cells) is essential for the initiation of somatic mutations, izotype switching and formation of memory cells • IL-4, IL-5, IL-6: stimulation of B lymphocytes

13. TH2 immune response – help to B-lymphocytes

14. Assistance to B lymphocytes Specific direct help to B lymphocytes: • TH2 lymphocytes assisting B lymphocytes that were stimulated by the same Ag, which caused the rise of TH2 • To stimulate the secretion of cytokines by TH2 cell is sufficient signal via the TCR (signal through a costimulatory receptor CD28 is no longer necessary) • One clone of TH2 cells can provide specific assistance to B lymphocytes of different specificities (must present the relevant Ag peptides by MHC gp II, which are recognized by TCR)

15. Assistance to B lymphocytes Indirect help to B cells ("bystander help"): • TH2 lymphocytes assisting B lymphocytes that were stimulated by another Ag than that which caused the rise of TH2 • Contact between TH2 cell → B lymphocytes via adhesion molecules, cytokine secretion, binding CD40-CD40L • Danger of activation autoreactive B lymphocytes

16. Mutual regulation of activities TH1versus TH2 • Whetherthe THprecursor cell willdevelopinto TH1 or TH2 decidescytokine ratio of IL-12 and IL-4 • IL-12isproduced by macrophages and dendriticcellsstimulated by certainmicroorganisms • IL-4 isproduced by activatedbasophils and mast cells • TH1 cytokines (mainlyIFNg) inhibitthedevelopmentof TH2 and stimulatethedevelopmentof TH1 (IL-2 stimulatesalso TH2) • Cytokinesproduced by TH2 (IL-4, IL-10) inhibitthedevelopmentof TH1 and stimulatethedevelopmentof TH2

18. TC based immune response

19. Cytotoxic T lymphocytes stimulation • TC recognize cells infected with viruses or other intracellular parasites, and some tumor cells • Precursor of TC, which recognizes a complex of MHC gp I- antigenic peptide on the surface of APC via TCR and receives signals via CD 28 proliferates and differentiates to clone mature effector cytotoxic cells (CTL); TH1 cells help to TC by production IL-2 • Effector TC are spread by bloodstream into tissues; for activation of cytotoxic mechanisms is sufficient signal through the TCR (signal through a costimulatory receptor CD28 is no longer necessary)

20. Tc effector functions • Cytotoxic granules containing perforin and granzymes (perforin creates pores in the cytoplasmic membrane of target cell, in some cases may lead to osmotic lysis of the target cell, formed pores in the cell receiving granzymes that cause the target cell to die by apoptosis. • Fas ligand (FasL) - which binds to the apoptotic receptor Fas (CD95) presented on the surface of many different cells (also on the surface of TC) • TNFb

22. Antiinfection immunity Jitka Ochotná

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

25. 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 caused 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) after infection persist IgG, IgA (protective effect) and memory T and B lymphocytes

26. in the defense against bacterial toxins apply neutralizing antibodies (Clostridium tetani and botulinum ...) 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

27. Defense against intracellular bacteria and molds mycobacteria, some yeasts and molds 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

28. plasma cells under the influence of IFNg produce IgG2, immune complexes containing IgG2 bind to Fc receptors on macrophages and thus stimulate • in the defense against intracelular parasites, which escape from phagolysosomes apply TClymphocytes • intracellular microorganisms infections are at risk individuals with certain disorders of phagocytes and defects of T lymphocytes

29. Defense against viruses 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)

30. Defense against viruses

31. 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 pathway of complement • IgA and IgG derived in viral infection have a preventive effect in secondary infection

32. effector TC lymphocytesdestroy 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

33. Defense against protozoa parasites Toxoplasma gondii, Leishmania, Trypanosoma defense against protozoa parasites is similar to bacteria extracellular parasites - antibodies intracellular parasites - TH1 lymphocytes and activated macrophages

34. Defense against multicelular parasites mast cells, basophils and eosinophils 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 in IgE

35. IgE bind to FceRI on mast cells and basophils (antigen-specific receptors) • 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) - histamine • activation of arachidonic acid metabolism (leukotriene C4, prostaglandin PGD2) - amplification of inflammatory responses • production of cytokines (TNF, TGF, IL-4, 5,6 ...)

36. 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)

38. Possibilities of the therapeutic effect on the immune system

39. Causal treatmenta)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 - the collection from shovel hip bone                                    - from umbilical cord blood                                    - from peripheral blood after stimulation with GM-CSF

40. 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

41. Substitution treatment autologous stem cell transplantation following chemotherapy 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

42. Non-specific immunomodulation therapyImmunomodulation = medical procedure to adjust the disrupted immune function a)non-specific immunosuppressive therapynonspecific = 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

43. 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, MHCgpII, adhesion molecules)                    - inhibition of histamine release from basophil                    - higher concentrations induce apoptosis - prednison, methylprednison immunosuppressants affecting the metabolism of DNA - cyclophosphamide (alkylating agent)                           - methotrexate (antimetabolite) - azathioprine (purine analogue)

44. immunosuppressant selectively inhibiting T lymphocyte                   - cyclosporin A (inhibits the expression of IL-2 and IL-2R in activated T lymphocytes) - tacrolimus, rapamycin - monoclonal antibody anti-CD3 (immunosuppression after transplantation, treatment of rejection crises) Immunoglobulins in the immunosupressive treatment

45. b)anti-inflammatory and antiallergic treatmentnonsteroidal 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)

46. c) non-specific immunostimulant therapyimunostimulancia - stimulate the immune system 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

47. products of the immune system - IL-2 - renal adenocarcinoma - IFNa, IFNb - viral hepatitis, some leukemia - Erythropoietin - G-CSF, GM-CSF - neutropenia thymic hormones transfer factor

48. Antigen-specific immunomodulatory therapy specific immunomodulation = induce immune response or tolerance to specific antigen • Active immunization • Passive immunization • specific immunosuppression

49. active immunization = use of antigen to induce an immune response that can later protect against a pathogen bearing the antigen (or antigen like him) immunization vaccines 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

50. 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 inducing anaphylactic reactions