Insufficient/overactive Immune Responce Flashcards
Outline Severe combined immunodeficien (SCID)
X chromosome linked disease, therefore more common in XY males. XX females are carriers. Patients lack functional T and B cells.
Results from defective gene involved in development of T and B cells
Is inherited/inborn autoimmune disease.
Outline Virus induced immune suppression
Measles, HIV and many other viruses interfere with normal host immune system
HIV targets and can kill CD4 T cells
This leads to a diminished level of CD4 cells thus unable to provide help for antibody and cytotoxic responses (No activation of B cells for antibody, and no activation of CD8 cytotoxic cells)
Outline human immunodeficiency virus (HIV)
HIV receptor is CD4 molecule on CD4 T cells
Infection leads to loss of CD4 T cells
CD4 T cells help both humoral (B cell/antibody) and cytotoxic responses
HIV infection impacts on immunity to microbes (fungi, bacteria, virus) and to cancer. Previously harmless pathogens become opportunistic
Outline autoimmune disease
Normally prevented by host mechanisms (B and T cells screen at bone marrow/thymus respectively)
Although the innate system can trigger autoimmunity or exacerbate autoimmunity, autoimmune attack is mediated by the adaptive immune response (auto reactive T and/or B cells
Outline immune tolerance
Immune tolerance is critical to avoid autoimmunity
The thymus acts to delete auto reactive T cells
In the periphery there are other mechanisms to ensure that auto reactive T and B cells are silenced
Failures (due to genes or triggering infection) in immune tolerance can lead to autoimmunity
Outline autoimmune rheumatoid arthritis
Auto reactive T cells and B cells attack self antigens present in the joints, resulting in distorted joints, cartilage thinning, inflammation
Outline autoimmune diabetes type 1
Insulin beta cells attacked/selectively targeted. Other islet cells may escape autoimmune attack.
Outline allergic reactions
Allergens are foreign antigens that trigger allergic reaction
Are normally harmless environmental antigens (pollen)
Chemicals can induce allergy (penicillin)
Range of outcomes, from hay reaver to systemic anaphylaxis
Outline mast cell involvement in systemic anaphylaxis
Mast cell release of inflammatory mediators cause over inflation in vital areas of the body, leading to organ shut down
Outline the allergic reactions effector response
Dendritic cells present remnant peptides from peanut proteins to helper T cells
Primed helper T cells activate B cells to secrete IgE
Secreted IgE binds to mast cell receptors (Fc receptors - bind constant region heavy chain of antibodies)
Binding of peanut proteins to FcR on mast cells triggers mast cell degranulation and release of histamine and other inflammatory mediators
Outline the process of mast cell triggering
Dendritic cell phagocytoses peanut allergen, break down to peptides. Dendritic cell then presents on MHC2 to peanut specific CD4 T cell, which releases cytokines to help trigger peanut specific B cell, activates into plasma cell producing peanut allergen antibodies.
Peanut specific IgE binds to mast cells. Peanut allergen binds mast cell surface IgE, triggering degranulation of mast cell, releasing histamines, cytokines, and other inflammatory mediators
Outline local allergic symptoms
Itching, swelling nausea, vomiting, cramping, diarrhoea
Outline systemic allergic symptoms
Airway obstruction
Hives
Low blood pressure
Arrhythmia
HIV targets…
CD4 T cells
Severe combined immunodeficiency (SCID) results in a loss of…
T cells and B cells
