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Immunodeficiency Diseases. Components of the immune response system are absent or nonfunctional Deficiencies involve B and T cells, phagocytes, and complement system Primary immunodeficiency Genetically based congenital lack of B-cell and/or T cell activity

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immunodeficiency diseases
Immunodeficiency Diseases
  • Components of the immune response system are absent or nonfunctional
    • Deficiencies involve B and T cells, phagocytes, and complement system
  • Primary immunodeficiency
    • Genetically based congenital lack of B-cell and/or T cell activity
      • B cell defect – agammaglobulinemia – patient lacks antibodies
      • T cell defect – thymus is missing or abnormal
    • Severe combined immunodeficiency (SCIDS)
      • Both parts of lymphocyte system are missing or defective No adaptive immune response
  • Secondary immune deficiency
    • Acquired
    • Due to damage after birth
      • Viral infections, drugs, radiation
slide2

Sequestered Antigen Theory

Sequestered behind anatomical barriers

Self reacting lymphocyte clones

Infection, trauma or deterioration

Some tissues are not scanned by the immune system during embryonic growth.

CNS, lens, thyroid & testes

slide3

Self antigens are sequestered and later incorrectly identified as foreign antigens by B lymphocytes

Failure of the fetus to eradicate all self-reacting lymphocyte clones (forbidden clones)

Another hypothesis: Immune Deficiency

B lymphocytes have defective receptors

Can not distinguish between self & non-self

slide4

Viral Infection Theory

Self antigens are altered by a viral infection

Produces an immune response against perceived foreign antigens

slide5

insulin-dependent

AutoAbs produced against b cells of the islets of Langerhans

T cells become specific for all the insulin-producing b cells in the islets destroy the cells and greatly reduce insulin synthesis

Hypothesized to be caused by viral infection

Cell receptor is altered by a viral infection

Immune cells attack that tissues bearing viral damaged receptor

Viral infections of the pancreas

Several viruses have been implicated but not conclusively demonstrated:

Mumps virus, rubella virus, hepatitis C

other autoimmune diseases
Other Autoimmune Diseases

Rheumatoid arthritis

AutoAb bind to the synovial membranes of joints

Chronic inflammation, scar tissue & joint destruction (page 516)

IgM anti-IgG antibody (rheumatoid factor)

Exact cause not known: Epstein Barr virus may play a role

Lupus

AutoAb against organs & tissues

Butterfly rash across nose & cheeks (page 516)

Kidneys, bones marrow, skin, nervous system, joints, muscles, heart, GI tract, nucleoprotein & mitochondria

Generalized loss of self tolerance

Exact cause not known:

Epstein-Barr Virus may play a role

more autoimmune diseases
More Autoimmune Diseases

Hashimoto thyroiditis

AutoAb & T cells reduce thyroid production

Hypothyroidism

HTLV-1

Graves Disease

AutoAb to receptors of cells in the thyroid that produce thyroxin

Overproduction of thyroxin

Hyperthyroidism

HTLV-1 (Human T-Lymphotropic Virus)

Multiple sclerosis

AutoAb & T cells damage myelin

Muscular weakness & tremors

Difficulties in speech, vision & paralysis

Hypothesis: Human herpes virus, possibly EBV

Myasthenia gravis

AutoAb bind to receptors of acetylcholine

Damages muscles  paralysis

Viral etiology proposed but none has been identified

herpes viruses
Herpes Viruses

www.cdc.gov

  • dsDNA linear genome
  • Enveloped DNA viruses
  • After entering the cells the capsid then travels along a microtubule to the nucleus
  • Binds to a nuclear pore
  • Viral DNA enters the nucleus through the pore and circularizes
  • Latency
    • May integrate into the host chromosome in a ganglia
  • Bud from the inner nuclear membrane
  • Envelope then fuses with the outer nuclear envelope and naked capsids enter the cytoplasm
  • Enter the into Golgi vesicles full of viral proteins
  • Capsid receives envelope in Golgi
  • Golgi vesicles delivers virions to the plasma membrane
  • New virus particle can infect another cell
  • Cause many diseases
slide9

Herpes simplex virus (HSV-1 + HSV-2)

    • oral herpes (cold sores)
    • genital herpes
    • congenital herpes (neonatal herpes) can cause blindness and neurological problems
    • keratoconjunctivitis (ocular herpes)
    • herpes encephalitis
    • herpes meningitis
  • Varicella-Zoster Virus (VZV):
    • chickenpox
    • shingles (herpes zoster)
  • Cytomegaloviruses (CMV) or Human herpesvirus 5 (HHV-5)
  • Human Herpes Virus 6 (HHV-6):
    • sixth disease / roseola infantum
  • Human Herpes Virus 7 (HHV-7)
  • isolated from T cells of AIDS patients but does not seem to cause a disease
  • Epstein-Barr Virus(EBV)
    • Hodgkin's Disease
    • Burkitt's lymphoma
    • Infectious mononucleosis (mono) or kissing disease
  • Human Herpes Virus 8 (HHV-8) or Kaposi's Sarcoma-Associated Herpesvirus (KSHV):
    • Kaposi's sarcoma

Herpes simplex HSV-1

Varicella-Zoster (VSV)

Epstein-Barr (EBV)

90% of the human population

slide10

Latency

The herpes simplex virus life cycle. (a) Herpes simplex virus (HSV) is shown undergoing the lytic cycle (entry, uncoating, viral transcription and DNA replication in the nucleus, particle assembly, exit from the cell) in epithelial cells of the skin to cause a primary infection. (b) Some virus enters the sensory neuron terminals and travels retrogradely to the nucleus where it establishes latency. (c) Periodic reactivation results in anterograde transport of viral particles, shedding from the neuron, and re-infection of epithelial cells, which leads to asymptomatic shedding or recurrent lesions.

Stress

Fever

Trauma

Sunlight

Menstruation

Infection

Immune suppression

Mucous membrane

www-ermm.cbcu.cam.ac.uk/fig001rlc.gif

HSV-1 & HSV-2

epstein barr virus
Epstein-Barr Virus
  • Worldwide distribution
  • Most people are infected by EBV
    • Estimated that 95% of U.S. adults between 35 and 40 years of age have been infected
  • Common childhood infection
    • Asymptomatic
    • Brief illnesses of childhood
  • B-lymphocyte infection
  • Linear virus genome circularizes
  • Virus subsequently persists within the cell as an episome
  • EBV infections during adolescence or young adulthood may causes infectious mononucleosis
    • Fever, sore throat, and swollen lymph glands
    • Transmission via saliva of an infected person
    • A lifelong dormant infection in B-lymphocyte
  • Causes Burkitt's lymphoma and nasopharyngeal carcinoma
    • Rare cancers that are not typically found in the United States
  • No antiviral drugs or vaccines are available
  • Chronic fatigue syndrome
    • Impossible to state that this is caused by EBV
    • Not plausible by the CDC

Cytotoxic T cells attempt to eliminate infect B cells

cancer
Cancer

New abnormal growth of tissue

≡ any of various neoplasms characterized by the proliferation of anaplastic cells that tend to invade surrounding tissue and metastasize to new body sites

A lack of differentiation

Spread to other regions of the body via blood and

lymph vessels or spinal fluid

neoplasms

Immune Surveillance

Majority of precancerous / cancer cells are destroyed:

NK Cells(natural killer cells)

Macrophages

TC Cells

Neoplasms
  • Benign
    • Noncancerous
      • Grow slowly
      • Retain surface recognition proteins
      • Remain in a home tissue
  • Malignant
    • Cancerous
      • Grow and divide abnormally
      • Disrupt surrounding tissues physically & metabolically
      • Mutated antigens escape detection
      • Retain self antigens
slide14

13.5

Causes of Death - Worldwide

slide15

Carcinomas

Originate in the outer layer of cells of the skin and

internal membranes. Examples include: breast, lung, intestinal,

skin & prostate cancer.

Sarcomas

Originate in connective tissue such as bone, muscle, cartilage &

blood vessels.

Lymphomas & Leukemias

Hematologic cancers

Blood or blood-forming organs such as the spleen, lymph nodes

& bone marrow.

slide18
An individual’s chance of developing cancer within his or her lifetime is almost twice as great today as it was 50 years ago
  • People are living longer
  • Cancer is more prevalent in older people
proto oncogenes oncogenes
Proto-oncogenes & Oncogenes

Normal Growth Control

Proto-oncogenes

Code for proteins that

stimulate mitosis

Oncogenes

Over-expression of proteins

that promote mitosis

tumor suppressor genes
Tumor Suppressor Genes

Tumor suppressor genes

Code for proteins that inhibit mitosis

No longer inhibit mitosis

p53 tumor suppressor gene

p53 that can trigger cell apoptosis

p53 Tumor Suppressor Gene

50% of all cancers

have an aberrant p53 gene

Normal cell

Cancerous cell

dna repair genes
DNA Repair Genes

DNA repair genes code for proteins whose

normal function is to correct DNA errors

Mutations in DNA repair genes can lead to a

failure in DNA repair, which in turn allows

subsequent mutations in tumor suppressor

genes and proto-oncogenes to accumulate

classes of carcinogens
Classes of Carcinogens
  • Physical
  • Chemical
  • Biological
  • Heredity
radiation sources

Nuclear medicine 4%

Consumer products 3%

Other 1%

Medical X rays 11%

Chemical

reactions

in the body

11%

Radon

54%

Other chemical

sources 8%

Cosmic waves 8%

Radiation Sources
biological causes

Some viruses carry oncogenes whose products cause transformation of host cells into cancer cells.

Viral genome may be inserted into regulatory sites.

Biological Causes
heredity and cancer
Heredity and Cancer

Cancer is not considered an inherited illness because most cases of cancer, perhaps 80 to 90 %, occur in people with no family history of the disease. However, a person's chances of developing cancer can be influenced by the inheritance of certain kinds of genetic alterations. These alterations tend to increase an individual's susceptibility to developing cancer in the future. For example, about 5% of breast cancers are thought to be due to inheritance of particular forms of a "breast cancer susceptibility gene”.

htlv 1 human t cell leukemia lymphoma virus type i

Nature Medicine 2004  10

J Clin Pathol 2000 53:581-586

HTLV-1Human T Cell leukemia/lymphoma virus type I
  • Oncogenic retrovirus
    • Two (+) sense strands of RNA
    • gag, pol & env genes
    • Tax
      • Transcriptional activator
    • Rex
      • Regulates viral mRNA splicing
  • Adult T cell leukemia (ATL)
  • Long list of autoimmune diseases
  • Infects from 15 - 25 million individuals world-wide
  • Endemic to south-western Japan, central portion of Africa, the Caribbean basin, central and South America, Melanesia, regions of Iran, southern India, aboriginal groups in Australia
  • Common among IV drug users
slide31
Three major modes of transmission
    • Breast milk
    • Sexual transmission
    • Blood transfusion
      • Blood is screened for HTLV-1
  • Similar to the Simian TLV-1
    • Chimpanzees and mandrill baboons
    • Transferred from animals to humans
  • Asymptomatic for as long as 50 years
  • CD4 T lymphocytes are the main target
  • Virus binds to the receptor for glucose
    • GLUT-1
  • Immunoassays are used to detect Ab made in response to the virus
  • No method to assess prognosis of asymptomatic infected individuals
  • No methods to assess risk
  • No treatment
    • Some success with interferons and AZT
  • No vaccine