Immunology Flashcards
What is the role of the thymus?
Site of T lymphocyte maturation (leave as either CD4+ helper cells of CD8+ killer cell) and selects and deletes auto-reactive cells to prevent autoimmunity. A primary lymphoid organ.
What are lymph nodes?
Nodular aggregates, located along the lymphatic system when the immune response is initiated and where antigen is concentrated having arrived via the lymph.
What is a type I hypersensitivity reaction?
Type I reactions (ie, immediate hypersensitivity reactions) involve immunoglobulin E (IgE)–mediated release of histamine and other mediators from mast cells and basophils. Examples include anaphylaxis and allergic rhinoconjunctivitis.
What are the hypersensitivity reactions?
4 types: Type I- Immediate hypersensitivity Type II-Antibody-mediated Type III-Immune complex mediated Type IV-T cell mediated
What is an organ-specific autoimmune disease?
Autoimmune attack versus self antigens of a given organ. This leads to damage of the organs structure and function. Examples: Type 1 diabetes mellitus, Goodpasture’s syndrome, MS, Graves Disease, Myasthenia Gravis.
What is a non-organ specific (systemic) autoimmune disease?
Widespread self-antigens are targets for autoimmune attacks. Damage effects structure such as blood vessel and cell nuclei etc. Examples: Rheumatoid arthritis, scleroderma.
What causes Graves disease?
Autoantibodies against the thyroid stimulating hormone receptor leading to hyperthyroidism- overproduction of thyroid hormones.
What is primary immunodeficiency?
The deficiency is the primary cause of the disease. Primary immunodeficiencies are usually congenital, resulting from genetic defects in component of the immune system. Most common class of primary immunodeficiency is in B lymphocytes/antibodies, 50% of cases.
What is secondary immunodeficiency?
Deficiency as acquired as a result of other diseases or conditions eh. HIV, malnutrition, immunosuppression.
What happens in transplant rejection?
T cells are activated against donor transplantation antigens, stimulated in peripheral lymphoid tissues, Both CD4 and CD8 cells.
What is the autoantibody target in Myasthenia Gravis?
Acetylcholine receptor.
What is the autoantibody target in Guillain-Barre syndrome?
Gangliosides (peripheral nerves). Triggered by infections including Campylobacter jejuni. Common cause of acute paralysis.
What are the 3 pathways to activate complement?
- Classical pathway.
- Lectin pathway.
- Alternative pathway.
How does the classical pathway to complement work?
Classical pathway- antibody binds to specific antigen on pathogen surface.
How does the lectin pathway to complement work?
Lectin pathway-Mannose binding lectin binds to pathogen surface.
How does the alternative pathway to complement work?
Alternative pathway-pathogen surface creates local environment conducive to complement activation.
Where are MHC class I proteins found and what cells do they present to?
MHC1 found on all nucleated cells and present to CD8+ T cells.
Where are MHC class II proteins found and what cells do they present to?
Restricted to DC, macrophages, B cells etc. (antigen presenting cells). Presents to CD4+ T cells.
What is an antigen?
Any molecule that can bind to an antibody or generate peptide fragments that are recognised by T-cell receptors.
What does the bone marrow do?
Produces red blood cells and lymphocytes. Site of haematopoietic stem cells- can give rise to all of the different mature blood cel types and tissues.
What happens in bone marrow failure?
The liver, thymus and spleen may resume their haemtopoeitic function. This is called extramedullary hematopoiesis. It may cause organs to increase in size substantially.
In the developing embryo where does blood formation take place?
Occurs in in the yolk sac then as the organs develop the spleen, liver and lymph nodes take over this task until finally bone marrow develops and makes the majority of blood cells.
