Insuffiecient or overactive immune response Flashcards
What is severe combined immunodeficiency (SCID) ?
X chromosome linked disease, therefore more common in XY-males. XX females are carriers. Patients lack functional T cell and B cells
What is virus induced immune suppression in regards to HIV?
Measles, HIV and many other viruses interfere with normal host immune system
HIV targets and can kill CD4 T cells
This leads to diminished levels of CD4 T cells unable to provide help for antibody and cytotoxic responses
What is 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 and cancer (patient can become more susceptible to microbes as can’t fight infection as well as before)
What is an autoimmune disease?
Caused by autoreactive B cells and T cells - when B cells and T cells rearrange they can become autoreactive/self reactive
Normally prevented by host mechanisms of immune tolerance
Innate system can trigger autoimmunity or exacerbate (make worse) autoimmunity
Autoimmune attack is mediated by the adaptive immune response
What is immune tolerance?
Immune tolerance is critical to avoid autoimmunity
The thymus acts to delete autoreactive T cells
In the periphery there are other mechanisms to ensure that autoreactive T and B cells are silenced/killed (peripheral tolerance)
Failures due to your genes or triggering infection lead to autoimmunity
What is Rheumatoid Arthritis (RA)?
An autoimmune disorder that primary affects joints
Autoreactive T cells and B cells attack self antigens present in joints
Affects ~1% of population often late onset in life
Can to some extent be controlled by anti-inflammatory drug
How is diabetes Type 1 related to autoimmunity?
Type 1 diabetes is a very selective autoimmune disorder
Insulin beta cells are attacked by T cells meaning insulin cannot be produced resulting in type 1 diabetes
What are allergic reactions?
Allergens are the antigens that trigger allergy
The foreign antigens are normally harmless environmental antigens
Chemicals e.g. penicillin can induce allergy
Can lead to hay fever to systemic anaphylaxis
What is the effector response in allergic reactions?
DC (dendritic cells) present peptides from allergens to helper T cells
Primed helper T cells activate B cells which recognises allergen and secretes IgE. Secreted IgE binds to mast cell receptors (FcR)
Binging of allergens to FcR on mast cells triggers mast cell degranulation and release of histamine and other inflammatory mediators
What is FcR?
Mast cell receptors that bind to the constant region of antibodies through the heavy chain
What does HIV target?
CD4 positive cells
Severe combined immunodeficiency is:
Inborn/genetic/inherited on X chromosome (more common in men as X-linked)
The percent of people in the US with peanut allergy is approximately what?
2%
Rate is continually increasing in the US, quadrupled since 1997-2010
