Module 4 Flashcards
Adverse Reactions and Immune Deffects
What is Immunodeficiency
Disorder or condition where the immune system has reduced function or is absent an can be traced to the failure of one or more parts of the immune system
What are the 2 main types of immunodeficiency?
Primary
Secondary
Describe primary immunodeficiencies
- Congenital
- Derive from a genetic or developmental defect leading to abnormal maturation of the immune system
- can be in either innate or adaptive immunity
- Most common kind is B-cell deficiencies
- rare because foetus rarely survives the defect
Why are primary immunodeficiencies so rare%
In most cases, foetus does not survive the defect
What are the 5 classifications of Primary immunodeficiencies?
1- B-cell deficiencies 2- T-cell deficiencies 3- Complement deficiencies 4- Phagocytic deficiencies 5- Combined T-cell and B-cell deficiencies
Describe B-cell deficiencies
- Characterized by dysfunctional B Lymphocytes or a decrease in their prevalence
- First symptoms generally appear around the age of 7-9 months old (when Mother’s antibody pool from mother decreases)
- Increased susceptibility to infection especially by encapsulated bacteria
- Example: X-linked agammaglobulinemia (XLA), where patients do not develop mature B-cells, low levels of IgG and lack all other immunobglobulins
Why do symptoms of B-cell deficiencies typically appear around 7-9 months old?
It is around 7-9 months that the antibody pool from the mother decreases, the incapability to synthesize normal levels of antibodies of the infant becomes apparent
Increase in susceptibility to infection, especially encapsulated bacteria is the result of what class of deficiencies?
B-cell deficiencies
X-linked agammaglobulinemia (XLA) is what type of immunodefficiency?
B-cell deficiencies
Describe X-linked agammaglobulinemia (XLA)
- B-cell deficiency
- X-linked and recessive, thus occurs almost exclusively in males
- Patients do not develop mature B-cells
- Low levels of IgG and lack all other immunoglobulins
- Patients are extremely susceptible to bacterial infections, but susceptibility to viral and fungal infections remains unchanged (cell mediated immune responses are normal)
Describe T-cell deficiencies
- Dyscfunctional T lymphocytes or a decrease in their prevalence
- Decreased cell-mediated immunity (which kills infected or abnormal cells)
- Increased susceptibility to viruses, protozoans, and fungi
- Frequent infections beginning 3-4 months after birth (eg: pneumonia, candidiasis)
Example: DiGeorge Syndrome
Describe Secondary immunodeficiencies
- Are acquired and result from environmental factors affecting/compromising the immune system
- Causes; chemotherapy, chronic infection (eg: AIDS), developing cancer
- AIDS is the most studied
What is the most studied secondary immunodefiency?
AIDS
Describe Complement deficiencies
Genetic deficiencies in complement components
- Prone to frequent severe bacterial infections and complications arising from inability to clear immune complexes
- Patients with C3 deficiencies display the severest symptoms, reflective of the central role played by this component in complement activities
Example: Hereditary Angionedema
Describe phagocytic deficiencies
remember phagocytes engulf and destroy pathogens
- Phagocytic deficiencies can appear at any steps of phagocytosis
- Bacterial and fungal infections are unusually frequent and severe, often causing deep abscesses
Example: Chronic Granulomatous (CGD)
Describe combined T-cells and B-cells deficiencies
- Dysfunctional and/or low numbers of lymphocytes
- Both humoral and cell-mediated responses are compromised (adaptive immunity)
- Little or no resistance to infection thus pathogens that cause mild diseases in average person (eg: chicken pox) may be life threatening
- Often suffer fatal infections within the 1st year of life
What kind of immunodeficiency is DiGeorge Syndrome?
T-cell deficiency
Describe DiGeorge Syndrome
- Caused by deletion of a small segment of chromosome 22
- Absent or underdeveloped thymus, which results in the absence of mature T-cells
- Also causes abnormalities in the heart, face, and palate + learning disabilities
Name a T-cell deficiency
DiGeorge Syndrome
Name a B-cell deficiency
X-linked agammaglobulinemia (XLA)
What kind of immunodeficiency is Hereditary Angioedema (HAE)
Complement deficiencies
Name a Complement deficiency
Hereditary Angioedema (HAE)
Describe Hereditary Angioedema (HAE)
- Dysfunction in the REGULATION of complement pathways
- caused by a lack of regulator of C1
- results in swelling of the face, lips, larynx, or GI tract. Swelling of larynx and GI trac are of particular concern because it can lead to suffocation
What kind of immunodeficiency is Chronic Granulomatous (CGD)?
Phagocytic deficiency
Name a phagocytic deficiency
Chronic Granulomatous (CGD)
Describe Chronic Granulomatous (CGD)
- Body’s phagocytes do not make the chemicals needed to kill the rest of the body
- Name derived from tendency of patient to form non-malignant granulomas in order to attempt to separate foreign materials from the rest of the body
Name a combined T-cell and B-cell deficiency
Severe Combined Inherited Immunodeficiency (SCID)
What kind of immunodeficiency is Severe Combined Inherited Immunodeficiency (SCID)
Combined T-cell and B-cell deficiency
Describe Severe Combined Inherited Immunodeficiency (SCID)
- Combined T-cell and B-cell deficiency
- David “Bubble Boy” Vetter lived in a bubble for 12 years (germ free). Passed away after a bone marrow transplant (intended to treat his disease) contained an unexpected infectious agent
What is the most well-known and studied secondary immunodeficiency?
AIDS
What does the acronym AIDS mean?
Acquired - not inherited
ImmunoDeficiency - breakdown of immune system
Syndrome - plethora of rare but ravaging diseases that take advantage of the body’s collapsed defences
What is the most common mode of transmission of HIV in;
1- North America
2- Africa
3- Eastern Europe/Central Asia
1- Sexual Intercourse
2- Heterosexual sex with a concomitant epidemic in children through vertical transmission (mother-to-child)
3- Non-sterile injecting drug paraphernalia
What are the stages of HIV infection? (4)
1- Primary Infection
2- Acute Infection
3- Chronic Infection
4- AIDS
Describe the primary infection stage with HIV?
Most people will mount an effective immune response to the virus for the first couple of weeks
This response will prove ineffective over time (through stages)
Describe the acute infection stage with HIV
HIV targets and infects cells with CD4 on their surface (including CD4+ Helper Tcells)
- Causes drastic decrease in the level of CD4+ Helper T cells while level of virus in the blood increases
- Within 2-4 weeks of exposure, some people will experience flu-like symptoms including fever, headache, and rash
Why do CD4+ Helper T cells level stop crashing after the acute infection?
Some antibodies are formed against the virus allowing the immune system to recover some of the lost cell population
Describe the Chronic infection stage with HIV (aka clinical latency)
HIV continues to multiply in the body at a steady state
- patients often do not experience symptoms but transmission is still possible
- anti-HIV antibodies are detectable during this phase, but HIV can begin to evade immune response by changing their antigens through high mutations rate
- duration of this phage is 8-10 years
Describe the AIDS stage of HIV
Throughout latency CD4+ Helper T Cells get “exhausted” and depleted by constantly fighting a chronic HIV infection.
AIDS is diagnosed when the CD4+ Helper T cell level are less than 200 cells/mm3
- Viral load drastically increases as the virus acquire mutations that allow it to further avoid immune defenses
- Immune System is severely weakened, patients become extremely susceptible to opportunistic infections
- In absence of treatments patients typically survive about 3 years
When was the first antiretroviral approved?
1987
How does antiretroviral therapy work?
It prevents the virus from replicating (does not kill it)
Utilizes a panel of antiretroviral drugs in different combinations to prevent drug resistance by the rapidly-mutating virus
- Led to declines of AIDS and AIDS associated deaths
What are screening techniques?
Methods or strategies used to identify the possible presence of a disease in individuals who may be pre-symptomatic or have unrecognized symptoms of the disease
- Allow for early intervention and management of the disease to reduce suffering and mortality