What is the primary target for AIDS screening? - what are some proteins that are important for infection? - why are these proteins important for infection?

Primary Screening Target: - gp24 Proteins important for infection: - gp41 - gp120 gp41 and gp120 are important for CD4 and CCR5 receptor binding on CD4+ T cells

Diseases of the Immune System Flashcards by Barrett Thompson

Name some lab values that suggest histoplasmosis?

- what is the pathohistology of histo?

Lab Values:

High Lactate Dehydrogenase - general indicator of tissue damage
High Ferritin - indicates liver damage

Pathohistology:

Histoplasmosis is found in macrophages
Much smaller in size than Lymphocytes

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Why is disseminated histoplasmosis an indicator of HIV/AIDS?

Immunocompetent people form caseating granulomas form to prevent dissemination
Immunocompromised people who get it will have disseminated infection if they lack TH1 cells/TH1 cell function

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What is the primary target for AIDS screening?

what are some proteins that are important for infection?
why are these proteins important for infection?

Primary Screening Target:
- gp24

Proteins important for infection:

gp41
gp120

**gp41 and gp120 are important for CD4 and CCR5 receptor binding on CD4+ T cells

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What is seroconversion?

Seroconversion happens when you are infected with a disease and your serum shows detectable amounts of Ab Specific to that bug

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What is the seroconversion rate for Hepatitis B? HIV?

Hep B = 6-30%

AIDS = 0.3%

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Why does HIV deplete T cells?

T cells are depleted because of the CYTOPATHIC effect of the virus (LYSES WHEN IT EXITS THE T CELL)

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How are APCs involved in in acquiring the HIV virus?

Dendritic Cells and Macrophages take up the HIV virus and present it to T-cells

***Macrophages are believed to Harbor the Virus because they are more resistant to the cytopathic lyses, thus the virus is not seen by the immune system

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Describe the Surface anatomy and Pathohistology of the lymphnodes of an HIV patient.

Surface Anatomy:
- Gross Lymph Node Enlargement

Pathohistology:

Atypical Shapes of germinal centers
Less cellular but Tingible Body Macrophages will still present

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What are some common infections of AIDS patients?

Cyptosporidiosis
Pneumocytosis
Toxoplasmosis

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Is it common to see a disseminated Penumocytosis infection?

NO, even in AIDS patients these will not be disseminated

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Why is JC virus seen often in AIDS patients?

JC virus is a common disease that people get in childhood but never disseminates

HIV permits dissemination

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What test is used to test for Cryptococcal infections?

- how does it work?

Cryptococcal Antigen Latex Agglutination System

Detects capsular polysaccharide antigen of cryptococcus neoformans in serum and in CSF

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What differentiates Nocardia infections from TB as far as histology goes?

Noricardia is Gram + in addition to be Acid Fast

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What often happens to viral infections in the immunocompromised?
- diseases that do this?

Normally localized infections like herpes disseminate

Herpes Simplex
Varicella Zoster

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How will a patient with a disseminated herpes virus of the face appear?

Vesicles are seen over the entire face with MULTIPLE DERMATOMAL DISTRIBUTIONS

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T or F: Shingles (varicella zoster) virus maintains its dermatomal distribution in HIV patients.

False, it will often disseminate

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What disease causes Kaposi’s sarcoma?

Human Herpes Virus 8

What are some common neoplasms seen in HIV patients?

Kaposi Sarcoma
Primary Lymphoma of the Brain
Invasive Uterine Cancer

What is Wasting Syndrome?

- what symptoms define it?

HIV complication that is defined as:

Loss of at least 10% of body weight
Diarrhea
Chronic Weakness
Fever

What is one of the most common neurological complications are associated with AIDS?
- symptoms?

AIDS demientia complex
Behavioral Changes
Diminished Mental Functioning

An AIDS patient succombs to diarrhea.

- what is the likely cause if this was a fungal infection?

Cryptosporidosis

Why do you suspect cryptococcus is responsible for so many CNS infections in AIDS patients?

Its an Encapsulated fungus

Encapsulated = meningitis

What is the role of CCR5 in non-HIV positive people?

- what happens to people who have a mutation in CCR5 when they are exposed to HIV virus?

CCR5 is a chemokine receptor that is needed by the HIV virus in order to infect.

If no CCR5 is present, then no/little susceptibility to HIV virus

How does HIV react when patients who are infected with HIV get a 2˚ infection?

Proinflammatory Signals via IL-1, IL-6, and TNF-alpha actually may promote HIV proliferation

*This makes since it is likely that more lymphocytes are trying to be synthesized in the pro-inflammatory state

What host cell is important for INITIATION of HIV virus in a host? - is the same cell important for getting it to the brain? - What about for maintenance of the virus?

Dendritic Cells: - Initiation and Maintenance - DCs are most important with presenting viruses to T cells and they are abundant under epithelial layers where infections begin Macrophages: - Important for communiting with Microglial Cells (macrophages of the brain) and getting the virus to the CNS that way

Differentiate a histological findings in a lymphnode biopsy of a person recently infected with HIV from someone with a lymphoma.

HIV lymph node will have the following not found in lymphomas: • Tingible body macrophages • Mantle Zone (darker ring of cells around lighter center - aka T cells surrounding B cells) • Atypical Shape (this would likely be seen in lymphomas too)

What is the significance of Tingible body macrophages being present in a lymph node?

I indicates that proliferating cells in the lymph node are still dying.

During the acute (symptomatic phase) of HIV infection, what is happening to the virus? - host immune system? - what happens post-acute phase?

- During the Acute Phase (1-3 weeks post exposure) patients have flu-like symptoms - Virus Shoots up and becomes prolific - Host immune system is suppressed - After the Acute phase and Until the onset of AIDS the T cell count comes back up and virus decreases

T or F: cryptosporidosis sits on the surface of enterocytes.

False, while it appears that it sits on the surface it is actually INSIDE the enterocyte on the apical surface

At what white cell count do you typically start to see patients getting Pneumocystis jirovecii? - what are the symptoms? - what is the likelyhood of dissemination?

Count Less than 200 - Patients are often Asymptomatic - Very common opportunist * *Often you notice this because O2 saturation is low on room air Dissemination = NEVER

You see multiple ring-enhancing lesions and you suspect toxoplasmosis in an AIDS patient. - what does will IgG test for Toxo most likely reveal? - why would you take an IgM?

- IgG will most likely be positive for Toxo whether or not the lesions are being caused by Toxo because Most people Carry Toxo, it just gets re-activated in AIDS patients - IF test is negative you might want to start thinking more about Glioblastomas - IgM is pointless - if they have toxo in the brain its from a re-activation event

What is a major risk factor for getting Toxo?

- Having a Cat

If someone has thrush and they have AIDS what symptoms might they have?

- Upper Abdominal Pain - Difficulty Swallowing - Chest Pain

Why do AIDS patients often present with Subacute cryptococcal infections?

- They are immunosuppressed so they don't experience symptoms until the disease has progressed

Differentiate packaging of Histoplasmosis and Coccidiomycosis.

Coccidiomycosis is packaged in ENDOSPORES (large) Histoplasmosis is NOT packed it sequesters in MACROPHAGES

Pigeons give you Crypto.

You have AIDS and get a Mycobacterium Avium infection. - what virus is this most likely complexed with? - what will your symptoms be? - How would you Dx.

Mycobacterium intracellulare and avium infect together Symptoms: - Lack of Appetite - BULKY ABdominal Lympadenopathy Dx. - Colonoscopy biopsy or Lymph Node Biopsy would be needed to make a dianosis

What disease starts as a cavity forming pneumonia that progresses into neurological symptoms?

Nocardiosis

At what T cell count do you start to see AIDS patients with White matter Lesions? - what disease is causing this? - Prognosis? - Histo?

T cells less than 50 Opportunist: - JC virus - causes progressive multifocal leukoencephalopathy Prognosis: - AIDS patients can live with this for years Histo: - Glassy Inclusions from the virus that can be stained with IHC stain as well **What matter lesions can cause you to walk funny etc.

What markers would you use to see if someone had Kaposi's Sarcoma? - why? - what are your looking for?

Markers for Kaposi's: - CD31 - CD34 Why: - You will see a lot of Blood cells in the Histological section - CD31 and CD34 are blood vessel markers - If you stain for CD31 and 34 and the cells are not located in blood vessels then its likely Kaposi's

What 3 common neoplasms do you see in AIDS patients?

Kaposi Sarcoma Primary Lymphoma of the Brain Invasive Cancer of Uterine Cervix

Why are Viral Drugs for viruses other than HIV often not effective in patients who have HIV?

- Drugs that patients are taking for HIV have likely selected for very Drug Resistance strains of other viruses that the patient may be infected with