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Immune SystemImmune System Disorders Disorders
What is an allergy anyway?What is an allergy anyway?
Response to antigens (allergens) Response to antigens (allergens) leading to damageleading to damage
Require sensitizing dose(s)Require sensitizing dose(s)
Hypersensitivity Hypersensitivity ReactionsReactions
Involve IgE Involve IgE antibodiesantibodies
Localized: Localized: Hives or Hives or asthma from asthma from contact or contact or inhaled inhaled antigensantigens
Systemic: Systemic: Shock from Shock from ingested or ingested or injected injected antigensantigens
Type I (Anaphylactic) Type I (Anaphylactic) ReactionsReactions
Figure 19.1a
Skin testingSkin testing DesensitizatDesensitizat
ionion
Type I (Anaphylactic) Type I (Anaphylactic) ReactionsReactions
Figure 19.3
Involve IgG or IgM antibodies and Involve IgG or IgM antibodies and complementcomplement
Complement activation causes cell Complement activation causes cell lysis or damage by macrophageslysis or damage by macrophages
Type II (Cytotoxic) Type II (Cytotoxic) ReactionsReactions
Hemolytic Disease of Hemolytic Disease of the Newbornthe Newborn
Figure 19.4
Drug-induced Drug-induced Thrombocytopenic Thrombocytopenic
PurpuraPurpura
Figure 19.5
IgG antibodies and antigens form complexes IgG antibodies and antigens form complexes that lodge in basement membranesthat lodge in basement membranes..
Type III (Immune Complex) Type III (Immune Complex) ReactionsReactions
Figure 19.6
Delayed-type Delayed-type hypersensitivitihypersensitivities due to Tes due to TDD cellscells
Cytokines Cytokines attract attract macrophages macrophages and initiate and initiate tissue damagetissue damage
Type IV (Cell-Mediated) Type IV (Cell-Mediated) ReactionsReactions
Figure 19.8
Clonal deletion during fetal Clonal deletion during fetal development ensures self-tolerancedevelopment ensures self-tolerance
Autoimmunity is loss of self-Autoimmunity is loss of self-tolerancetolerance
Autoimmune DiseasesAutoimmune Diseases
Type I — Due to antibodies against pathogens
Type II — Antibodies react with cell-surface antigens
Type III (Immune Complex) — IgM, IgG, complement immune complexes deposit in tissues
Type IV — Mediated by T cells
Autoimmune DiseasesAutoimmune Diseases
Histocompatibility antigens: Self Histocompatibility antigens: Self antigens on cell surfacesantigens on cell surfaces
Major histocompatibility complex Major histocompatibility complex (MHC): Genes encoding (MHC): Genes encoding histocompatibility antigenshistocompatibility antigens
Human leukocyte antigen (HLA) Human leukocyte antigen (HLA) complex: MHC genes in humanscomplex: MHC genes in humans
Reactions Related to the Human Reactions Related to the Human Leukocyte Antigen (HLA) ComplexLeukocyte Antigen (HLA) Complex
Diseases Related to Diseases Related to Specific HLAsSpecific HLAs
Table 19.3
HLA TypingHLA Typing
Figure 19.1
Transplants may be attacked by T Transplants may be attacked by T cells, macrophages, and complement-cells, macrophages, and complement-fixing antibodies.fixing antibodies.
Transplants to privileged sites do not Transplants to privileged sites do not cause an immune response.cause an immune response.
Stem cells may allow therapeutic Stem cells may allow therapeutic cloning to avoid rejection.cloning to avoid rejection.
Reactions to Reactions to TransplantationTransplantation
Autograft: Use of one's own tissueAutograft: Use of one's own tissue Isograft: Use of identical twin's tissueIsograft: Use of identical twin's tissue Allograft: Use of tissue from another Allograft: Use of tissue from another
personperson Xenotransplantation product: Use of Xenotransplantation product: Use of
non-human tissuenon-human tissue Graft-versus-host disease can result Graft-versus-host disease can result
from transplanted bone marrow that from transplanted bone marrow that contains immunocompetent cellscontains immunocompetent cells
GraftsGrafts
Cyclosporine suppresses IL-2Cyclosporine suppresses IL-2 Mycophenolate mofetil inhibits T cell Mycophenolate mofetil inhibits T cell
and B cell reproductionand B cell reproduction Sirolimus blocks IL-2Sirolimus blocks IL-2
Immunosuppression Immunosuppression prevents an immune prevents an immune
response to transplanted response to transplanted tissuestissues
Congenital: Due to defective or missing Congenital: Due to defective or missing genesgenes Selective IgA immunodeficiencySelective IgA immunodeficiency Severe combined immunodeficiencySevere combined immunodeficiency
Acquired: Develop during an Acquired: Develop during an individual's life, due to drugs, cancers, individual's life, due to drugs, cancers, infectionsinfections Artificial: Immunosuppression drugs Natural: HIV infections
Immune DeficienciesImmune Deficiencies
Cancer cells possess tumor-specific antigensCancer cells possess tumor-specific antigens TTCC cells recognize and lyse cancer cells cells recognize and lyse cancer cells
Cancer cells may lack tumor antigens or kill TCancer cells may lack tumor antigens or kill TCC cells cells
The Immune System and The Immune System and CancerCancer
Figure 19.11
Treatment of cancer using Treatment of cancer using immunologic methodsimmunologic methods
Tumor necrosis factor, IL-2, and Tumor necrosis factor, IL-2, and interferons may kill cancer cellsinterferons may kill cancer cells
Immunotoxins link poisons with an Immunotoxins link poisons with an monoclonal antibody directed at a monoclonal antibody directed at a tumor antigentumor antigen
Vaccines contain tumor-specific Vaccines contain tumor-specific antigensantigens
ImmunotherapyImmunotherapy