General Pathology (autoimmune & immunodeficiency diseases / neoplasia) Flashcards
autoimmune diseases
break down of tolerance of AG on own cells (SELF-AG)
diagnosis of autoimmune disease
auto-Antibodies
immune mechanisms cause pathological lesions
can be difficult to find evidence of immune nature of disorder
“pathogenicity difficult to prove”
AI disease genetic factor
increased frequency via Family history
genetic component
more common in
women
E.g.
SLE
RA
systemic vs localized
can be systemic or local
how localized?
E.g. of systemic (multi-organ) AI disease
systemic lupus erythematosus
rheumatic fever
rheumatoid arthritis
systemic sclerosis
polyarteritis nodosa
E.g. of AI diseases limited to single organ (more localized)
multiple sclerosis (CNS)
Hashimoto’s thyroiditis (thyroid)
Grave’s disease (thyroid)
Autoimmune hemolytic anemia (blood)
Pemphigus vulgaris (skin)
Myasthenia Gravis (muscle)
Systemic Lupus Erythematosus
“prototype of AI disease”
multisystemic
1/2500 people
10x more common in women
genetic component (family history?)
more common in young adults
but can happen any age
signs symptoms
CNS symptoms
pattern baldness
butterfly rash
Endocarditis, Pericarditis
Pleuritis, Pneumonitis
lupus nephritis
raynaud’s phenomenon
myositis, arthritis
osteoporosis
splenomegaly
lymphadenopathy (lymph nodes, aka lymph glands)
anemia, neutropenia, thrombocytopenia
pathogenesis SLE
poorly understood
Malfunction of T suppressor cells which allows polyclonal activation of B cells
“Plasma cells derived from uncontrolled B cell clones secrete antibodies against autoantigens and foreign antigens”
“Many antibodies to DNA, RNA and nuclear proteins = called antinuclear antibodies (ANA)”
antinuclear antibodies (ANA)
“The antinuclear antibody (ANA) is a defining feature of autoimmune connective tissue disease. ANAs are a class of antibodies that bind to cellular components in the nucleus, including proteins, DNA, RNA, and nucleic acid-protein complexes.”
Agab complexes during SLE
Antigens that reach circulation form complexes with antibodies in the serum
“Circulating Ab-Ag complexes deposited in membranes e.g. synovial membrane, serous membranes, endocardium, choroid plexus, ant. eye chamber”
E.g.
synovial membrane (joints)
serous membranes (heart, lungs, abdomen)
endocardium
choroid plexus (brain)
anterior eye chamber (eyes)
atnerior eye chamber sle
“Anterior uveitis in patients with SLE is usually mild and rarely leads to a deterioration in visual acuity, and also may present as synechiae or a fibrinous inflammatory exudate in the anterior chamber of the eye.”
complement system activation vs immune complexes
“Immune complexes are large and retained and activate complement, which elicits an inflammatory reaction resulting in many organ-specific inflammatory diseases”
e.g.
glomerulnonephritis,
arthritis,
etc
clinical features sle
variable
Inflammation of joints (arthritis) – most common; redness, swelling, pain
Kidney involvement (75%)
Cutaneous lesions (butterfly rash) (30-60%)
Damage to RBCs causing anemia
Enlargement of lymph nodes and spleen
treatment sle
Corticosteroids
cyclophosphamide (immunosuppressive)
cyclophosphamide
“a synthetic cytotoxic drug used in treating leukemia and lymphoma and as an immunosuppressive agent.”
sle and kidneys
kidney transplant as treatment if kidneys severely affected
immunodeficiency
Primary (congenital) or
secondary (due to infections, metabolic diseases, cancer, or treatment/chemotherapy, etc.)
which type of immunodeficiency more common
secondary
cancer, infection, chemotherapy, metabolic disease
E.g. of secondary immunodeficiency
AIDS
acquired immunodeficiency syndrome
involvement of B/T cells vs entire immune system
Primary or secondary may involve just B cells or T cells
or may be generalized and involve the whole immune system
how are ID diseases characterized
All ID diseases are characterized by lymphopenia – low lymphocyte count in peripheral blood
lymphopenia
low lymphocyte count in peripheral blood
B cell deficiency
associated with low levels of serum antibodies
(low plasma, low AB production)
reduced resistance to infection
All ID disorders cause reduced resistance to infections
primary ID diseases
genetic disorders affecting differentiation and maturation of T cells and B cells
when occur?
Can occur at any step along the developmental sequence that leads from stem cells to fully differentiated cells
leads to
Leads to heterogenous group of disorders with mild or severe symptoms
e.g. primary ID disease
DiGeorge’s syndrome
T-cell deficiency related to aplasia of thymus, associated with aplasia of parathyroid glands
aplasia
the failure of an organ or tissue to develop or to function normally.
AIDS
Acquired immune deficiency syndrome
Set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV)
what does AIDS do
Progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumours
HIV transmitted how
transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV
Transmission can involve sex, blood transfusion, contaminated needles, exchange between mother and baby during pregnancy, childbirth, breastfeeding, or other exposure to bodily fluids
HIV how?
sex
blood transfusion
contaminated needles
between mother/baby during pregnancy
during childbirth
breastfeeding (virus in breastmilk)
exposure to bodily fluids (semen, pre-ejaculate, etc.)
direct contact?
direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV
certain bodily fluids
epidemiology
..
etiology HIV
RNA retrovirus
retrovrius define
RNA viruses that have an enzyme (reverse transcriptase) capable of making a complementary DNA copy of the viral RNA, which then is integrated into a host cell’s DNA. The family includes a number of significant pathogens, typically causing tumors or affecting the function of the immune system, e.g. HIV.
why called retrovirus?
While transcription was classically thought to occur only from DNA to RNA, reverse transcriptase transcribes RNA into DNA. The term “retro” in retrovirus refers to this reversal (making DNA from RNA) of the usual direction of transcription.
where highest prevalence?
Africa
how many worldwide
35 million
how many new cases per year
100,000 in US
percentage of college students
1% (18-25)
An estimated 3% to 6% of U.S. college students are HIV positive (different source)
HIV pathogenesis
Transmitted through the transfer of body fluids
Virus can’t survive outside host cell
HIV has affinity for T helper cells and monocytes (macrophage outside BV)
…
Macrophages can also become infected …
other cells infected
Fixed tissue phagocytic cells can also become infected (e.g. microglia)
what do infected cells do
Infected cells can serve as reservoir for virus
what happens to infected cells often/eventually
HIV virus is cytotoxic thus infected cells often die
hiv initial infection
Initial infection stimulates B cells to produce antibodies within weeks
hiv latent phase
The second stage of HIV infection is chronic HIV infection (also called asymptomatic HIV infection or clinical latency). During this stage, HIV continues to multiply in the body but at very low levels. People with chronic HIV infection may not have any HIV-related symptoms
hiv latency vs AIDS onset
Latent infection can persist for years
As virus replicates and destroys more helper T cells, symptoms of AIDS begin to appear
immunity during AIDS
Cell mediated immunity becomes depressed and humans cannot defend against infections (opportunistic infections)
Death generally occurs due to infection but can also occur due to tumours
phases of hiv
acute (inital infection)
chronic (latent)
crisis (AIDS)
acute
primary infection
sharp increase in presence of HIV virus in blood
sudden decrease in presence of CD4+ helper T cells in blood
acute stage lasts a few weeks
chronic/latent stage – and crisis stage
after immune system responds with antibodies to HIV
there is huge dip in presence of virus in blood
there is an increase in CD4+ helper cells (not to original amount, but close)
during actual clinical latency there is a relatively small presence of HIV virus in blood
presence of CD4+ helper cells very gradually declines throughout many many years
at the end of clinical latency, the amount of CD4+ helper cells decline to an extent that they can no longer contribute to defending against HIV virus (antibody production)
at this stage, virus overtakes immune system, and AIDS symptoms appear (crisis stage)
virus level increases and CD4+ level continues to decrease, until opportunistic infections/diseases lead to death
how long can latent stage be
chronic/latent stage = many many years
how long crisis stage
also can be few years
viremia
the presence of viruses in the blood.
“uncontrolled virus proliferation leads to chronic viremia”
4 phases of illness (hiv/aids)
..
Phase of acute illness (Group I)
Usually 3-6 wks after exposure
Symptoms typically non-specific, include fever, night sweats, nausea, myalgia, headache, sore throat, skin rash, lymph node enlargement
Symptoms last 2-3wks, then disappear
Pt. develop antibodies to HIV
Phase of asymptomatic infection (Group II)
Variable duration, months to years
theoretically can last a long time, and allow patient to live a relatively full life with currently available medicine/treatment
Asymptomatic patient carries virus and is infectious
Approx. 50% of HIV+ patients develop AIDS within 10 years of initial diagnosis if untreated
Phase of generalized lymphadenopathy (III)
Persistent lymphadenopathy develops in asymptomatic pts or early in disease
May persist for months or years
AIDS (Group IV)
Pt shows signs of AIDS which reflect opportunistic disorders including GI disorders, CNS involvement, neoplasia
Clinically, ratio of CD4+ /CD8+ cells decr.
In the last stages, almost no CD4+ cells present
–>
opportunistic diseases and death
AIDS define
AIDS is defined as HIV infection that leads to any of the disorders in clinical category B or C of HIV infection or a CD4+ T lymphocyte count of < 200/μL.
(less than 200 per cubic mm – aka microlitre)
The normal CD4 count range is between 500 and 1400 cells/microliters., taking into consideration laboratory variations.
disorders in clinical category B or C of HIV infection
Serious opportunistic infections
Certain cancers,
such as Kaposi’s sarcoma and
non-Hodgkin lymphoma,
to which defective cell-mediated immunity predisposes
Neurologic dysfunction
pathology..
Non-specific; vary with time, extent of viremia and degree of immunosuppression
@ lymph nodes
Initially lymph nodes enlarge and show hyperplasia
After time, lymph nodes become depleted of lymphocytes and eventually become infected
After time, lymph nodes become depleted of lymphocytes and eventually become infected (decreased CD4+)
@ brain
Microglia in the brain and multinucleated giant cells form nodules
Opportunistic infection leads to meningitis or encephalitis (CMV, herpes, fungi, protozoa)
May destroy part of the brain directly or through infarct
@ respiratory tract
Initially localized to URT but often progresses to LRT (pneumonia or TB)
–> Pneumocystis jiroveci/carinii (named after individuals)
cyst vs abscess
“While a cyst is a sac enclosed by distinct abnormal cells, an abscess is a pus-filled infection in your body caused by, for example, bacteria or fungi. The main difference in symptoms is: a cyst grows slowly and isn’t usually painful, unless it becomes enlarged.”
pneumocystis pneumonia define
fungal infection in one or both lungs. It is common in people who have a weak immune system, such as people who have AIDS.
@ GI tract
Infections are similar to respiratory tract and can also include parasites
Diarrhea and malabsorption of nutrients can also be present
@ skin
Can include dermatitis or infections (fungi, herpes, bacteria)
tumours
Often lead to mortality
Increased incidence of tumours esp. lymphomas (lymph nodes, spleen, liver, brain, etc.) and Kaposi’s sarcoma
pathologic findings in AIDS
meningitis
encephalitis
AIDS dementia
herpes labialis (more frequent/severe outbreaks)
thrush
pneumonia
malabsorption
colitis
proctitis (anus, rectum)
dermatitis
folliculitis
impetigo
Kaposi’s sarcoma
AIDS nephropathy
lymphomas
lymphadenopathy
Kaposi’s sarcoma
Malignant disease of endothelial cells
Caused by herpesvirus
Often occurs in skin and internal organs
Nodules composed of anastamosing vascular spaces filled with blood
Can cause bleeding or compress vital organs
diagnosis
Presence of HIV antibodies in blood (HIV+)
T cell count – decreased ratio of CD4+ /CD8+ (less than 200 per nanolitre of CD4+)
AIDS diagnosed by presence of opportunistic infection and tumours
treatment
Medications - replication inhibition (of virus)
Expensive & not readily available worldwide
Vaccines unsuccessful
Amyloidosis (disease)
Caused by deposition of a fibrillar substance called amyloid
Multi-factorial disease
Often related to abnormalities of the immune system or an abnormal response to chronic infection
Amyloid: any fibrillar protein that forms a beta-pleated sheet
where amyloid deposited
Amyloid is deposited in the extra-cellular spaces
Changes the function of tissues and cells
Deposits in blood vessels changes their permeability
Leads to proteinuria in kidney
Vessels in liver and adrenal glands becomes solid
amyloidosis – what happens
Atrophy and loss of cell function
Amyloid in heart causes weakened contractions
Amyloid in brain causes dementia
Clinical presentation is variable and depends on the organ system involved
No effective treatment
(treat symptoms as they appear)
Clinical Presentation of Amyloid Deposition
Systemic amyloidosis: usually caused by deposition of AA or AL amyloid in various organs (e.g., liver, kidneys, adrenals, spleen, heart)
Localized organ: specific amyloid deposits (e.g., Alzheimer’s disease)
LECTURE 6
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neoplasm
new growth
“Uncontrolled cell growth whose proliferation cannot be adequately controlled by normal regulatory mechanisms”
neoplasm define
“An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should. Neoplasms may be benign (not cancer) or malignant (cancer).”
“Benign neoplasms may grow large but do not spread into, or invade, nearby tissues or other parts of the body.”
normal cell gorwth requires
genetic material, aka DNA and RNA
signals from one cell to another
growth inhibiting or growth promoting substances
1) genetic material
2) signaling
3) growth inhibiting/promoting substance
differentiating
Once a cell stops growing it needs to differentiate - to become specialized -
by activating some genes, and suppressing other genes
tumour cells vs differentiation
Tumour cells do not achieve the same level of differentiation as normal cells
neoplastic cell growth
Autonomous - independent of normal growth factors and inhibitors
Excessive - doesn’t respond to normal regulators
Disorganized – compared to the formation of normal tissues
1) independent
2) excessive
3) disorganized
benign/malignant neoplasm (tumour)
enign – limited growth potential and good outcome
Malignant – grow uncontrollably with poor outcome