Immunosuppression Flashcards
What is immunity?
Complex system for controlling body integrity.
How is humoral and cell-mediated immunity different?
The major difference between humoral and cell-mediated immunity is that humoral immunity produces antigen-specific antibodies, whereas cell-mediated immunity does not. T lymphocytes, on the other hand, kill infected cells by triggering apoptosis.
How is innate and specific immunity different?
The innate immune response is activated by chemical properties of the antigen. Adaptive immunity refers to antigen-specific immune response. The adaptive immune response is more complex than the innate. The antigen first must be processed and recognized.
What are antibodies?
An antibody, also known as an immunoglobulin, is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen.
What are cytokines?
Cytokines are a broad and loose category of small proteins important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrine, paracrine and endocrine signaling as immunomodulating agents.
What are complement molecules?
The complement system, also known as complement cascade, is a part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen’s cell membrane.
What are the functions of the immune system?
prevent and fight infection
eliminate tumours
What are the main reasons for immune dysfunction?
Hypersensitivity (vigorous reactions to substances that are not harmful)
Autoimmunity (immune system attacks own cells)
Immune deficiency (autoimmunity can be the first manifestation of immune deficiency)
What is reduced immune status ?
Immunosuppression
Immunocompromised
Immunodeficiency
Classified as either congenital or acquired.
What is HIV?
Human Retrovirus, Lentivirus family
Gp120 binds to CD4 receptor
long latency
profound effect on immune function
What is AIDS?
Acquired Immune Deficiency Syndrome
What is the clinical spectrum of HIV infection?
Primary infection (seroconversion illness/infectious mononucleosis-like)
Asymptomatic
Progressive generalised lymphadenopathy
AIDS-Related Complex
AIDS
What is AIDS-Related Complex?
Low grade pyrexia
Persistent lympadenopathy
Night sweats
Weight loss
Diarrhoea
Oral Candidosis
What is AIDS?
Disease
Suggestive of severe cell mediated immune defect
Occurs in patients in whom there are no other known cause of immunosuppression
A CD4 T cell count of less than 200 x 106 cells per litre
Being HIV positive and suffering infections/cancers typical of the immunosuppressed.
What are the general features of AIDS?
1981 Recognised
Wide geographic variation
High risk groups
What is the situation with HIV in NI?
40% due to heterosexual contact
What are the clinical features of AIDS?
Non-specific systemic illness
low grade fever
lymphadenopathy
B symptoms
infections (e.g., diarrhoea/superficial skin infections)
Neurological conditions
What are the lab investigations involved in the diagnosis of AIDS?
Lymphopenia
Thrombocytopenia
HIV antibodies
Serology for other blood borne viruses
What is the biology of HIV?
enter susceptible cells via CD4
reverse transcribes RNA into DNA
- initially episome in cytoplasm
- enters nucleus
- binds and integrates into host DNA
proviral dna transcribed
new virions assembled
virus released into blood
pace of replication variable
initially very high levels of virus in the blood
immune response kicks in
variable levels of virus in blood
as disease progresses, multiple strains arise
What are the immune consequences of HIV?
T cell paralysis
polyclonal B cell stimulation
opportunistic infections
tumours e.g., kaposi’s sarcoma/NH lymphoma
Autoimmune conditions e.g., SLE like and thrombocytopenia
What is HIV therapy?
aims to reduce circulating viral load
recovery of immune function
Highly Active Anti-retroviral Treatment (HAART)
Lifelong Tx - rebound viraemia
How is HIV diagnosed?
SPUR infections (serious/persistent/unusual/recurrent)
Oral manifestations of asymptomatic HIV pts
Oral candidosis
Hairy leukoplakia
Oral pigmentation
Salivary gland enlargement
Oral manifestations of symptomatic HIV pts
Oral ulceration
AUG
Severe dental infections
xerostomia
atypical viral infections
Oral manifestations in AIDS
Kaposi’s sarcoma
Non-Hodgkin’s lymphoma
Kaposi’s sarcoma
Viral driven proliferation of lymphatic endothelial cells that grows like a tumour
ill defined bruise
painless
non-hodgkin’s lymphoma
Non-Hodgkin lymphoma is a type of cancer that develops in the lymphatic system, a network of vessels and glands spread throughout your body.
