Transcript PM Immune Diseases

Dr ROOPA
Premed 2
Pathophysiology
IMMUNITY
 The term immunity refers to the resistance exhibited by the
host towards injury caused by microorganisms and their
products..
 Natural or Non-specific Immunity
 Respone 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 memory
 Exposure 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 System
 Primary Lymphoid organs
 Secondary Lymphoid organs
 Cells
 Cytokines
 Complement system
 HLA 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 presensitized (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.

Hypersensitivities
 Type I : immediate, anaphylactic
 1st exposure to an antigen: stimulates IgE to bind to
mast cells, basophils
 2nd exposure: IgE causes lysis of the cells, release of
histamine
 Allergic asthma, atopic dermatitis, seasonal rhinitis,
systemic anaphylaxis
 Type II: antibody-mediated or cytotoxic
 Antigens are bounded to human basement
membranes in tissues
 Or to blood cell membranes
 Antibodies, COMPLEMENT react to the antigens,
 NK cells may add on to the injury
 Type II hypersensitivity
 Hemolytic disease of the newborn
 Blood transfusion reactions
 Goodpastures syndrome: kidney and lung
abnormalities
 Type III: immune complex mediated
 Antigen is NOT part of the cell, or basement
membrane
 Immune complex: antigen+ antibody
 Very insoluble, not removed by macrophages
 Deposited on vessel walls, extravascular sites
 Type III
 Systemic lupus erythematosus (SLE)
 Serum sickness
 Arthus reaction
 Poststreptococcal glomerulonephritis
 Type IV: delayed hypersensitivity, cell-mediated
 CD4 cells react to MHC Class II
 Memory cells
 2nd exposure to antigen: stronger reaction
 CD cells may also be involved
 Type IV
 Tuberculin test
 Contact dermatitis
Transplant reactions
 Matching ABO blood group
 Matching HLA antigens
 Organs that can be transplanted:
liver
kidney
lungs
bone marrow
skin
 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 rejection
 Hyperacute: 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 disease
 Common in bone marrow transplant
 Immunocompetent cells in the transplant (graft)
 Host cells are damaged by:
CD8+ cells
cytokines
macrophages
 Organs damaged: liver, skin, GIT
 Fever, rash, large liver, jaundice
Primary Immunodeficiency diseases
 X-linked agammaglobulinemia
 Or Bruton’s agammaglobulinemia
 Male babies, more than 6 months old
 Absent plasma cells
absent germinal centers
absent IG
 Prone to bacterial infections
IgA deficiency
 Most common B cell defect
 1 in 700 persons, Caucasians
 May be with no symptoms (asymptomatic)
 Recurrent Upper respiratory tract infection (URTI)
and frequent diarrhea
Severe Combined Immunodeficiency
Disease (SCID)
 Low B cells and T cells
 Absence of ADA (adenosine deaminase) or PNP (
purine nucleotide phosphorylase): enzymes which
remove metabolites in lymphocytes
 Severe infections
 Treatment: gene therapy
Systemic Lupus Erythematosus (SLE)
 Antibodies against nucleic acids in the connective
tissues (antinuclear antibodies or ANA)
 Women
 Immune complex deposits:
kidneys
joints
skin
lungs
serous membranes
SLE
 Wire-loop lesions in the kidneys (subendothelial
layer)
 Eye lesions
 Fever, body pains, joint pains
 Pericarditis/pleuritis
 Raynaud phenomenon
 Endocarditis
 Libman-Sacks vegetations on mitral valve