Upload
prudence-underwood
View
213
Download
1
Tags:
Embed Size (px)
Citation preview
Dr ROOPAPremed 2
Pathophysiology
IMMUNITYThe term immunity refers to the resistance
exhibited by the host towards injury caused by microorganisms and their products..
Natural or Non-specific ImmunityRespone is antigen-independent There is immediate maximal response Not antigen-specific Exposure results in no immunologic
memory
Acquired or Specific Immunity Response is antigen-dependent There is a lag time between exposure and
maximal response Antigen-specific Exposure results in no
immunologic memoryExposure results in immunologic memory
The key primary lymphoid organs of the immune system are thymus and bone marrow, and secondary lymphatic tissues such as spleen, tonsils, lymph vessels, lymph nodes, adenoids, and skin.
Normal Immune SystemPrimary Lymphoid organsSecondary Lymphoid organsCellsCytokinesComplement systemHLA system
The complement system is a biochemical cascade that helps clear pathogens from an organism.
The diseases caused by disorders of the immune system fall into two broad categories: immunodefeciency, in which parts of the immune system fail to provide an adequate response (examples include chronic granulomatous disease),
and autoimmunity, in which the immune system attacks its own host's body (examples include systemic lupus erythematosus, rheumatoid arthritis, Hashimoto's disease and myasthenia gravis). Other immune system disorders include different hypersensitivities, in which the system responds inappropriately to harmless compounds (asthma and other allergies) .
Hypersensitivity refers to excessive, undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. Hypersensitivity reactions can be divided into four types: type I, type II, type III and type IV, based on the mechanisms involved and time taken for the reaction. Frequently, a particular clinical condition (disease) may involve more than one type of reaction.
HypersensitivitiesType I : immediate, anaphylactic1st exposure to an antigen: stimulates IgE to
bind to mast cells, basophils2nd exposure: IgE causes lysis of the cells,
release of histamineAllergic asthma, atopic dermatitis, seasonal
rhinitis, systemic anaphylaxis
Type II: antibody-mediated or cytotoxicAntigens are bounded to human basement
membranes in tissuesOr to blood cell membranesAntibodies, COMPLEMENT react to the
antigens, NK cells may add on to the injury
Type II hypersensitivityHemolytic disease of the newbornBlood transfusion reactionsGoodpastures syndrome: kidney and lung
abnormalities
Type III: immune complex mediated Antigen is NOT part of the cell, or basement
membraneImmune complex: antigen+ antibodyVery insoluble, not removed by macrophagesDeposited on vessel walls, extravascular sites
Type IIISystemic lupus erythematosus (SLE)Serum sicknessArthus reactionPoststreptococcal glomerulonephritis
Type IV: delayed hypersensitivity, cell-mediated
CD4 cells react to MHC Class IIMemory cells2nd exposure to antigen: stronger reactionCD cells may also be involved
Type IVTuberculin testContact dermatitis
Transplant reactionsMatching ABO blood groupMatching HLA antigensOrgans that can be transplanted:
liverkidney lungsbone marrowskin
Histocompatibility antigen test
histocompatibility antigen blood test looks at proteins called human leukocyte antigens (HLAs), which are found on the surface of nearly every cell in the human body. HLAs are found in large amounts on the surface of white blood cells. They help the immune system tell the difference between body tissue and foreign substances.
Types of transplant rejectionHyperacute: OCCURS IN MINUTES
-due to preexisting antibodies to donor antigens
Acute: OCCURS DAYS TO WEEKS-due to T cells
Chronic: OCCURS MONTHS TO YEARS- antibodies will form to the antigens in the donor cells
Graft-versus-host disease (GVHD) is a complication that can occur after a bone marrow transplant in which the newly transplanted material attacks the transplant recipient's body.
Graft-versus-host diseaseCommon in bone marrow transplantImmunocompetent cells in the transplant
(graft)Host cells are damaged by:
CD8+ cellscytokinesmacrophages
Organs damaged: liver, skin, GITFever, rash, large liver, jaundice
Primary Immunodeficiency diseasesX-linked agammaglobulinemiaOr Bruton’s agammaglobulinemiaMale babies, more than 6 months oldAbsent plasma cells
absent germinal centersabsent IG
Prone to bacterial infections
IgA deficiencyMost common B cell defect1 in 700 persons, CaucasiansMay be with no symptoms (asymptomatic)Recurrent Upper respiratory tract infection
(URTI) and frequent diarrhea
Severe Combined Immunodeficiency Disease (SCID)Low B cells and T cellsAbsence of ADA (adenosine deaminase) or
PNP ( purine nucleotide phosphorylase): enzymes which remove metabolites in lymphocytes
Severe infectionsTreatment: gene therapy
Systemic Lupus Erythematosus (SLE)Antibodies against nucleic acids in the
connective tissues (antinuclear antibodies or ANA)
Women Immune complex deposits:
kidneys jointsskinlungsserous membranes
SLEWire-loop lesions in the kidneys
(subendothelial layer)Eye lesionsFever, body pains, joint painsPericarditis/pleuritisRaynaud phenomenonEndocarditisLibman-Sacks vegetations on mitral valve